You're agreeing to different outcomes as I've presented them. JL pulling in BvS numbers isn't the categorical failure that it currently is now.
That wasn't the scenario you presented. You presented a scenario in which a JL with no prior DCEU films preceding it would have performed as well as it is performing right now. We're comparing the JL that exists with MoS, BvS, SS, and WW to a JL that exists without those films. I concluded that both films would have produced the same results.
If a hypothetical (DCEU debuting) JL film does much better than what we have now with the same exact content and negative press, your claim that (this) JL has failed on its own merits is null and void.
But I didn't agree a DCEU debuting JL film would do much better than what we have now. I agreed that it would have done as well as the real JL is doing right now. If I think the same product would produce the same results regardless of what does or does not precede it, then I am very much arguing that JL is responsible for its own success and failure. I was not talking numbers or bottom line but was speaking to the dynamic you described of a film that underperformed based on its potential and overperformed based on its reception. I was not agreeing that a DCEU debuting JL would have made as much money as BvS.
Look, there's no need to overcomplicate this. If I pose a simple question, "If JL had been critically acclaimed, would it have been more successful than the version that is in theaters now?" My answer would be "Yes." That answer tells me that BvS isn't the trump card or deciding factor when it comes to JL's success. If I pose another question, "If JL had been successful, does that mean BvS was actually well-liked by audiences?" My answer would be "No." Again, because JL's success would be something that is ultimately determined most by its own reception from critics and viewers.
To add another wrinkle, I hypothesize that a Snyder cut of JL would have been more profitable (this means altogether with total gross and total budget considered) than the current version, because at least extra money wouldn't have been spent, bad press wouldn't have happened as much, and Snyder fans might have been more satisfied. I don't think it would have done substantially better than what JL is currently doing, but I do think it would have done better.
Finally, if it's believed that BvS doomed ANY version of JL to its current fate, and that is something anyone thinks was a foregone conclusion even before JL was reviewed and released, then there is no scenario in which the film should have ever been made let alone had extra money spent on retooling it in what you're all describing as a futile effort.