Agreed completely. Another point that I don't think gets brought up enough is the prevalence of walkoffs, a stage type that intrinsically gimps certain characters and removes an entire facet of play (edgeguarding). It's notable that Smash 64 only had one and it was that game's "bonus stage" of sorts, but the stage type has only become more and more common as the franchise has gone on. Likely because it's easier to conceptualize as "part of an existing world", but with less concern for the consequences of play.
There's always been quite a lot of pushback against the stage, but it's only now that such pushback is having an effect.
Plenty of stages are banned for having intrusive hazards.
Much lower skill ceiling because you would get randomly killed by things and every decent strategy would be camping on the many, many stages that are conducive to it. It would be boring and not at all fun.
Non-obtrusive hazards offer a benefit to the skill ceiling by allowing people to work around them - someone might be able to see a Smashville balloon coming and use it as a weak shield, for instance. As opposed to the Yellow Devil, which is rather more difficult - and rather less fun - to work around.
It seems like there are a lot of relatively-small changes they could make to Smash 4 to greatly increase its competitive viability - some stage work, standardizing how custom moves work (like an official version of the custom moves project), and standardizing Miis, as a few small examples. I hope they do at least some of that, as I'd honestly love an excuse to get back into competitive Smash 4. It was just too mentally taxing to play a game competitively when it was so blatantly obvious that the creators had no interest in competitive play at best and seemed to actively dislike it at worst.