Glad we're having this discussion.
Last year I began to learn fighting games for the first time, and boy is it obtuse.
In the past month, I've really gotten into SFV and I'm enjoying it a ton! I've seen my game improve and that's an amazing feeling.
However, none of it was easy to come by mostly just because the game itself did very little to teach me how to play it, as if the devs didn't know.
I only see this level of obtuseness in fighting games, which is probably why most players I know IRL don't play any aside from Smash.
Games as a whole have made great strides to make themselves accessible without dumbing the down the content, or removing depth.
Fighting games mostly have remained unchanged in their learning structure (in that there isn't much of one).
I get that it was cool in the Arcade to see someone throw a Hadoken/do a fatality for the first time, wonder how they did it, and then figure it out yourself.
But in 2017 people can pick up satisfying multiplayer games without that hurdle, so fighting game devs need to step their game up.
Training modes with key inputs, recordable CPUs, and attack data have been useful, and replays for online matches are fantastic.
However, one generally still needs to understand both frame data and when a move is supposed to be used to really learn the game. The latter, can be done by trial and error to some extent, but even then one can be doing it wrong and not noticing.
The former is pretty much metagame, as fighting games don't slow themselves down to 1/60th speed and show you hit boxes ever, as far as I know.
I'm not asking that all information about playing a fighter be in the game. I doubt that's even possible as players are constantly discovering new knowledge on playing the game.
I do think, however, that the games should be able to teach you basic competency from the in game content. Things like anti-air, footsies, what the hell "crush counter" means.
Even as Arms just came out, which is a more simple game than most fighting games, most of its reviews criticized the game for doing a poor job as explaining some its basic fundamentals.
The answer to making fighting games more approachable isn't dumbing them down, as much as it is having the game give you basic information that any experienced player could just explain to you if you're lucky enough to know them.
People shouldn't have to go to YouTube.