I assume the reference is to failed starts at cinematic universes e.g. The Amazing Spider-Man 2, the Tom Cruise The Mummy, and Batman v Superman/Suicide Squad/Justice League. The sort of things where they tried to front-load a whole crossover mythology in the first or second film and neglected to make the film itself good enough that the audience wanted more. I think suarezguy is misinterpreting that as a reflexive rejection of non-Marvel CUs, which is certainly not the case. It's just that any cinematic success will spawn a ton of imitators, most of whom do it badly.
Although there are some more successful CUs out there. There's the sprawling Fast and Furious franchise and the Conjuring thing mentioned above. The Legendary MonsterVerse seems to be doing okay. Even Venom seemed to be enough of a box-office success that the "Sony Universe of Marvel Characters" is still going forward, even though it was critically trashed.
I mean, Mummy was one movie. Sure it wanted to start a universe, but it unequivocally failed to do so by a *wide* margin (that obviously can't just be attributed to 'marvel fans'). There is literally no shared universe there to judge. I'd say the same about Spider-man, as well, and that one didn't even spend that much time setting anything up - just a few scenes here and there to let you know the Sinister Six would happen. It was still too much, especially since Rhino made every scene he was in 50 times worse, but most of the movie was about Peter and Gwen/Electro/Goblin, ie, the main story (which also sucked, except for Gwen - and that's why the movie is remembered badly).
I'm honestly kind of confused at the idea that F&F is 'cinematic universe'.. Aren't they all Fast and Furious movies? I mean, I know the cast has changed over time, but is it really that different between the films? (Granted there is a spin-off coming out, so I suppose there's a CU coming if not already there.)
Venom is also not a universe yet, and not really an 'attempt to launch a universe' storywise - the film was pretty much entirely self-contained - though it was definitely a trial balloon and seems very likely to lead to one. That one I actually honestly don't like and hope it's not representative of the Sonyverse to come, but again, I still currently have no CU to judge either way.
And of course, the DCEU was already discussed - though I wouldn't necessarily even guarantee that that one's 'dead' or 'failed' just yet. Those movies clearly did not do what they were supposed to, but they did still successfully launch Wonder Woman and Aquaman plus Harley Quinn and the Suicide Squad at the very least. And while it currently seems highly questionable whether those characters will really still be part of an ongoing CU (IE, actually crossover between each others' films or in team-up films), we don't really know with certainty yet that they won't.