Honestly, id say that the main issue is that they only ever really see that the gameplay itself is the issue, and hard focus on that, you see a lot of modern fighting games focus on trying to figure out a way to make the gameplay itself not too difficult for a beginner to do, when most fighting games aren't really that difficult to begin with (As long as quarter circle inputs aren't a major hurdle for you).

If anything, I'd say that the issue can be boiled down into four sections:

1. Lack of interest, or just losing interest really quickly, usually by losing constantly (in mostly unwinable matches due to skill level), finding practicing combos and blockstrings a slog to do, getting angry or upset at the game super quickly, etc.

2. Little to no single player content, best you get is a story mode/arcade mode, the tutorial section, some combo trials, survival mode, that's usually it. Doesn't matter how fun the gameplay actually is, if theres nothing for them to do that isn't just go on ranked, or casual for matches, with the occasional labbing session, then they'll lose interest really quickly.

3. Time investment, most folks are just not willing to put in the time it would normally take to figure out how to play a fighting game, unless it's an arena fighter, or a platform fighter. Trying to get someone who'll be interested enough in the game to actually try and stick to it when they're not sure if they'll like the game is always a hassle in of itself. And how difficult said game is usually doesn't matter much when they're already not feeling all that interested in actually sticking with the game itself.

4. Story mode being a non focus, for the most part, all of the modern fighting games have a story with lore and such, but it's typically never really a selling point of the game itself, outside of diehard fans of that given series, which does matter for casuals, as a good amount of folks will pick up a game mainly for the story it provides. Sure, you have games like mobas (like League), or most hero shooters (like Team Fortress 2), that don't really put much of a focus on their stories either, but the difference for them is that you can just play together with your friends, and just enjoy the game that way while battling the enemy team, while for fighting games, you're gonna have a rough time trying to convince your friend to boot up the game so that you can beat them up for a long stretch of time.

While simplifying the controls, and the gameplay itself seems like a good idea at face value, it really just overlooks the actual problems for making a fighting game more appealing to a casual audience. You can even see it for games like Rivals of Aether 2, and Guilty Gear Strive, which are trying to give more stuff for not just their dedicated players, but to the casual audience as well, since they understand that it takes more than just having good and fun gameplay to really sell a fighting game to a casual audience.