It's either that people seem to think that every game in this genre has to have its quality determined by Smash in some way or corporate greed getting in the way.
Honestly, and correct me if you think I'm wrong, but an issue I have is that a lot of platform fighters end up intentionally structuring themselves more like Smash and shedding off some of what makes them stand out. This is an issue I personally have with the genre and I kind of end up groaning whenever I see games add say, a Smash shielding system added when they didn't have one before. Which I recall Multiversus doing a few months ago.
I'm disappointed that Multiversus seemed to largely stop prominently promoting its strongest hook, its team-based gameplay. Even within that second trailer, where the first focused on fun ways for the characters to assist and bounce off one another (sometimes literally), the second had more instances of everyone just taking turns. Where the beta sought to add characters that complimented one another, the official release seemed to be more concerned with its standalone fighters. Not inherently a problem, but that was an indication to me that the focus had shifted.
I'm sure someone who played the game more avidly than I did can tell me this part never really went away, and I'm curious to hear a more informed viewpoint. But I would have honestly doubled down on it further, and stressed all the ways Multiversus' unique gameplay style offers opportunities that Smash cannot. It's only natural that a big mascot crossover platfighter will invite Smash comparisons, and it's somewhat naive to imagine that Smash Ultimate isn't the basis for games like this and NASB existing in the first place. But say, having support oriented characters felt like something outside the bounds of Smash, and the team proceeded to kind of abandon that over time - wasn't the support class entirely scrubbed? And most newcomers, if I recall, were assassins and bruisers.
So I dunno, at that point it reads to most people as simply Smash with WB characters. And I don't think I can really blame anyone for thinking that.
Admittedly, maybe people would be more open to trying diverse movesets if, you know, characters were easily accessible…
This is how I feel about it too, because if Smash is any indication most people are willing to expose themselves to unfamiliar characters with fun creative movesets if they're dealt them. In fact, Smash proves that people are even willing to pay money for them since that trust has already been built. But Smash is able to sustain a consistent playerbase off a roster of like 70 characters available out of the box, and Multiversus... not so much.
If you're going to put in all that time, or fork over that kind of money to play as a character then in a game like Multiversus I think it's generally fair to have higher standards for who and what you're investing in.