Because really, are they good for anything else?
Anyway, exhibit 2744. Sure, it starts out innocently enough with Baby Park (which is a damn good track, definitely more than meets the eye), but the start of #9's entry is one of the dumbest things ever. "I don't really like Neo Bowser City." Since this was clearly written after MK8 came out, the author had 136 tracks to choose from. And he doesn't really like number 9 out of 136. Um, why are you playing Mario Kart again if the maximum number of tracks you like is eight out of 136? It's especially weird considering he'd never put it in a top 8, DESPITE BEING NINTH. So this guy clearly loves the fuck out of exactly eight tracks in the series, and can pick a favorite out of all the other ones. Despite "not really liking it", mind you.
And what about #7? Rainbow Road from FUCKING SUPER CIRCUIT? Super Circuit as a whole is an absolute disgrace to the rest of the series, and Rainbow Road is no exception. Hell, he spends a good portion of his paragraph blasting the hell out of it. And at the end, he still has the gall to invoke nostalgia. Of course. NOSTALGIA MAKES EVERYTHING BETTER. Except it never ever really does. I guess he also had to uphold that "at least one from each game" honor code bullshit you typically see in top tens. Why do top list writers do that? Top ten means top ten, not "top ten except for anything that doesn't fit some stupid arbitrary rule".
Later, he says "Nintendo apparently dreads the idea of putting GBA and SNES Retro tracks into their Mario Kart games". Well of course, these are the two worst ones by a country mile, so having many of their subpar tracks clog up the roster of retro tracks is a BAD IDEA. Of course they tried adding some extra twists to make up for it, such as an anti-gravity part in GBA Mario Circuit and Monty Moles and slippery ground in Donut Plains 3, but I can definitely do with less SNES and Super Circuit and more of everything else.
And of course, N64 Rainbow Road at #2. Do I need to say anything? No, because I already did. So you mean to tell me this boring ride of absolute nothingness is better than 134 tracks out of 136? BULLSHIT. Also nostalgia. Which is the same thing, really.
At least I can't really argue against Mount Wario being a good track. Sure, I'm horrible at it, but it's my own fault, not the game's. Is it my favorite? No, not at all. But at least there's a legitimate reason why it would be someone's favorite, as opposed to fucking N64 Rainbow Road which everyone has a diamond-hard boner for.