While its easy to just say that Nintendo (and by virtue Smash) fans are in a bubble, I think the context is a little trickier than that. About two years ago, there was a Twitter dustup started by this thread:
But I think phenomenon like this is a case where there's many factors; putting the cart before the horse (YouTubers can only do so much in shaping the culture), Croc not enduring for many players, and one other major element that also I think affects perceptions in Smash speculation. The thing is nostalgia, continuity, & reverence of past games is essentially baked into a lot of Nintendo's IP's in general. Trophies/spirits in Smash, stages in Mario Kart, highlighted titles on the online service, etc. The company makes you very aware of its titles and their legacy is so consistently brought up that even non first party games like Banjo-Kazooie fall into the (company created, fandom continued) sphere of remembering and appreciating what came before.
That's not to say they're the only company that does this, but so many various other publishers and developers have major games that have fallen by the wayside and aren't reinforced by a PR culture of recalling them that a YouTube retrospective about them isn't happening with that much frequency. Sega is one of the most famous game companies out there and half of their IP's are in deep hibernation or barely remembered because they were only big in certain regions.
And when you get to really old stuff like Atari or the British microcomputer scene, it gets worse because there's no effective media or delivery system to even tell people that titles from the time were good and/or popular. There's no contemporary piece of gaming media to introduce new generations or remind old ones about the releases on ZX Spectrum or Amstrad CPC, and so they increasingly become the domains of older niche fans while the Nintendo legacy/nostalgia culture becomes self reinforcing again and again.
Nintendo is only one of the biggest video game companies in the world, its also one that has a strong sense of historical continuity that eventually flows in the fandom (specifically the Western one) significantly as a result, expanding the reach of games far beyond what their sales reflected and naturally (albeit unintentionally) shutting out series outside that paradigm to a degree.