I'd say the heyday of the Snyder era was the time between the announcement and the making of BVS. And playing devil's advocate a little, it's easy to identify the source of this "trauma" for that fanbase. Things happened so dramatically at every turn, more than you ususally see with the average movie franchise.
I was never onboard with the Snyder style post-MOS, but it's hard to deny the sense of excitement/possibility that you had going during the making of BVS. Every rumor about Nightwing, Flash, Doomsday, Metallo, Jason Todd, etc, had people positively salivating. The WB message was, "This'll be filmmaker-driven. Every project will get the prestige TDK approach. And serious stories like 'Devil in a bottle' won't just amount to Tony Stark peeing in his armor for a one-scene gag". It was the antidote for whoever perceived the Marvel flicks as excessively light, and folks picked teams proudly.
Then BVS came out and this "us vs. them" narrative kicked in full blast. It was first Fans vs. Critics, then Art vs. Studio, then Snyder vs. Whedon, what have you. The firing of Snyder in such tragic circumstances... I can't think of a more dramatic development in any other nerd IP. They latched onto the notion of fighting the good fight, "This is what they took from you!!!", and never let go. The crazier fans get painted as the default setting of the group, but aggro dorks who like picking fights is sth you'll see everywhere on the net... it's not unique to them. But the Snyder crowd does have an interesting, often understandable trajectory for this weird online identity of theirs.
