For me, it's because the Space Chase plotline has the most inadequate writing of the film. It's not quite like there's one massive plot hole in the thing, but it is like there's a lot of medium sized issues that compile to make it the most juvenile plotting in the film, even more than the still sloppy and chopped down Finn plot. I'm not going to attack the physics of the chase, since Star Wars has never incorporated actual physics laws well enough to really get angry at laser's that fall off after a certain distance or perplexing speed and acceleration questions.
To start off, the Space Chase involves a few large issues that I subjectively disagree with and find to act against its dramatic purpose. First off, it's strictly a one dimensional, comparatively slow speed chase; there's no jukes, no turns, nothing to make it visually interesting. Second, the film wants this tense chase scene to both be tense and yet long enough to encompass the timeline of the film; an 18 hour straight line chase, one long enough for multiple parties to drop out and drop back in, lacks the intesity *you* found in it for myself and others. And since the bombardment of the Raddus is rendered ineffective by the distance between the ships, we don't have the feeling of them being worn down like they did in the Battlestar episode where they're constantly having to fight and repair their ship.
Those first two are largely subjective, but the third is where you enter possible plot hole territory: the lack of reasoning for why the chase even continues.
Why no TIEs?
The film tries to say that the Raddus and its fleet can escape capital ship bombardment and thus the TIE fighters must withdraw... But there were only three TIE Fighters deployed, including Kylo's, and the two SF TIEs were the ones that cracked open the bridge of the Raddus like a bad egg. And we know that regular Star Destroyers carry plenty fo thane SF TIES from TFA, so why aren't they being deployed en masse? And since we just exited a space battle that demonstrated how capital ship weaponry is not guaranteed at all to destroy multiple fighters, so even the perfunctory shot of Kylo's wingmen getting blown up feels negligible. So there's really no good reason why this film's First Order, depicted as far more Empire-like in its overwhelming resources than it was in TFA, doesn't just swarm the fleet with TIEs, especially since there's no fighter cover for the Resistance.
And all that's being generous and not finding it stupid that the FO doesn't have medium-sized support craft.
Head them off at the pass!
The film never provides an adequate explanation for why no Star Destroyers just hyperspace in front of the Raddus, either just immediately in a straight line, or after withdrawing to another system, then dropping right in front of them. We know you can get that specific, both in the trilogy from Han's landing on Starkiller Base and from this very movie; both Finn and Rey pilot their respective vehicles (the Libertine and the Millennium Falcon) through hyperspace and right to the Supremacy. Clearly, you can immediately catch up to the Raddus. There's nothing stopping you.
The only logical explanation I've heard for both of these issues is that Hux really is a dumb@$$, and not even a usual one like you'd see on Rebels; he's somehow even less logical than their comedic characters. And that significantly lowers any threat he or the First Order are supposed to have in this film, and glaringly contrasts with the Imperials in ESB and Hux himself in TFA.
How not to write Poe's plotline
Poe's plotline is already on shaky ground alongside Finn's; the idea of using two secondary plots to again hammer home the whole "failure is the best teacher" lesson is soaring towards redundancy, and towards face-playingly bad if you don't write them well. And they're not; the character at the center of the Raddus plot, Holdo, is written not as a character but as a trope device. When Johnson wants the audience in Poe's side and tricked into thinking that Finn will have something significant to do, he writes Holdo as your classic flawed Neidermeyer military officer; while an officer would have the right to refuse to give a recently demoted captain prove legend information, there's no damn good reason not to brief a stressed and worried crew about what the plan is, or at least to excuse why it's not shared. This is an officer who has a clear flaw in the land of fiction; that's why the audience turns on her at first. Then, suddenly, when Johnson wants to try springing his trap on you, he suddenly shifts gears and tries to write Holdo as the righteous authority figure; she spouts out some oxymoronic fortune cookie line about how Hope is best when it unknown, and suddenly is portrayed as in the right the whole time. We skip past the fact she clearly has actual flaws that even some real world military personnel would find serious; there is a moral and political element to command, and shushing people and sending them back to their stations before staring out a window is not going to meet that element.
But this is then exacerbated because the other twist Johnson tries to pull to reveal what plan Holdo and Leia have and what makes it the "smart play" falls flat on its face upon any inspection, because it's colossally stupid. They've been pursued in a straight line for literally almost a whole day, and we find out they've been aiming towards a planet here, out in the vast emptiness of space. Any idiot in the First Order is going to presume that means they're heading to that planet. And any moderately imaginative officer is going to recommend leaving significant forces at Crait on that possibility, and just pursue the Raddus with a still overwhelming fleet. So already, the plan is on shaky ground, since it depends on the FO ignoring the planet. Second, the film's depiction of cloaking is wholly sensor based; there's no attempt to establish a visual component. So the plan also depends on no one in the First Order looking out the window. Maybe you want to argue that it's too far away for the naked eye, but there's these great things called cameras and telescopes, like the one Snoke has and uses in the film for that purpose. Oh, and it turns out the FO can literally hit a few buttons and uncover any cloaking attempts... So why the hell don't they just constantly run that?!?
And all this so we can teach Poe a lesson and render all of Finn's story pointless because of DJ hearing something, and wrap it up with a visually spectacular but perplexing use of a hyperspace ramming tactic (they had four heroic characters in guard the Supremacy at that time, and they couldn't use even one of them to set up why the Raddus could do this but others ships couldn't earlier?!?). It's a badly plotted conflict with a badly plotted resolution, and you could in all honesty skip over all of it (or go to the bathroom them, like I did) and miss nothing with worthwhile craftsmanship out side of the acting.
