While I do generally think Smash lags behind a majority of, if not all, alternative platform fighters in most aspects (especially gameplay), I do think casual stages are a notable exception - while pretty much every other game has more visual variety in stages and a better lineup of competitive stages, Smash has way more layout variety for casual play. You wouldn't see a stage like Venom or Peach's Castle 64 in NASB or Rivals (forgivable in the case of the latter where even having casual stages is quite a surprise, and it's all made with sprites too)
I do feel that a lot of casual platform fighter stages tend to lack solid layouts, specifically because they like to avoid caves of life and walls. Often times they'll have a really cool casual stage mechanic but bog it down by just putting it into a Final Destination/Smashville clone instead of building a good stage layout to support it *cough*technodrome*cough*royal woods cemetery - though TBH Ultimate's new stages suffer from that too.
From what I can tell the general reasoning is that if anything happens to you whilst you're there, the people running the place are held mostly responsible for it, and that combined with a series of contractual agreements and a few weird legal holdovers whereever it is you may be (the UK in particular is really weird with this) but it's still really backwards (on their part)