*Quoting a post from the Mario matchup thread by @
Hinichii.ez.™
claiming Marth destroys Mario*
It is a good post with some little inaccuracies. I agree with most points, but you seem to underestimate that Marios neutral game is buffed by the fact that if the players move contrary because they both expected an attack Mario has the fireball again, and now you can stand at ~1.5 tipper f-smash lengths waiting for him to deal with it and then punish.
About projectile pressure, I normally think of it as two lines, one that signals that if you are closer you can't projectile without getting punished and the other one signalising the other player that if he is closer he can't choose easy evading options without getting punished.
Normally, the zone between these lines is a room for the approacher to utilize his entire neutral game toolset if it is the safe zone for him, and if the zone gives the projectile-player the advantage that causes the approacher to have serious problems surpassing that zone.
While normally Marth's ability to clank unpunished lasts longer than Mario's ability to fireball unpunished, while Marth is dashing back this is not the case. And in neutral game you often dashdance so that is a chance for Mario to capitalize.
One method to bait the dash back out is a low-distance WD back and then dash in (first to avoid the expected grab, and now you threaten a grab / run-cancel d-smash yourself. Marth probably doesn't want to commit to an attack so he will retreat, to which you will respond with a sh (hold back during jumpsquat frames) fireball. There are many more options to bait this out (many crouch setups to threaten CC while you need him to be unsure if his grab will miss because of your WD backs) if you dig deep into the meta.
Also, about your pressure, you also underestimate that whenever you force Marth into his shield you are probably able to weaken his stage position because of the WD back, even if you are not able to get the hit. If you then take space (little dash, WD with low distance forward) and continue neutral game, the chance of winning it will increase (less dash back abililties limit Marths options), the risk-reward ration turns even more in your favour because if you get hit there, your chances to recover are significantly worse.
Mario's huge combo ability on Marth doesn't get enough credit, and so does the fact you have to work for your kills less (d-throw/d-tilt ->fair, edgeguards).
Overall, your post is pretty good and I might be a bit nitpicky, the MU is still slightly advantegous for Marth but not a matchup to switch characters for, which is my main point.