Are fantasy sports on topic? No.
It goes back to the defining attributes of an RPG compared to other kinds of games: the emphasis on the shared fiction of play.
Fantasy sports is a game of research and strategy, akin to a more complicated version of sports betting. You pick players for your lineup, then wait for game results to figure out your hypothetical team's score. There's not even, like, a "session" really — AFAIK many people like to turn the initial draft into a party, but afterward you're just checking stats and occasionally trading with other players. You could imagine yourself as a team manager just like you can imagine yourself as a real-estate speculator in Monopoly, but this isn't a shared experience and it has no impact on situations or outcomes in the game.
Are make-believe games about [whatever] on topic? Maybe.
One could conceivably make and play a game an RPG or RPG-like game about sports or the music industry or whatever you like, of course! It's really not that weird of an idea.
Remember that the site is scoped to "tabletop, paper-and-pencil role-playing games." However, as far as I know, we've been pretty permissive about some TRPG-adjacent stuff like freeform play-by-post and solo roleplaying.
Some examples of previous meta questions about RPG-like games:
Deriving a standardized rule is dicey, but, here's me taking a shot at it:
This is a site about tabletop RPGs (including tabletop RPGs played online).
Questions about other RPG-like activities are generally in scope if they cover a facet of that activity that relates closely to tabletop roleplaying.
Are LARP questions on topic? Yes. (We just forget about LARP all the time.)
(Pureferret asked about this in the comments.)
LARP is mentioned in the FAQ — "Dungeons & Dragons, Dogs in the Vineyard, Shadowrun, World of Darkness, FATE, or any of the thousands of other pen-and-paper RPGs (including LARPs)" — but not on the Tour page.
My understanding is that LARP was always assumed to be in-scope because of the huge overlap between TRPGs and LARPs in terms of player base, subject matter, and even techniques, but it's not very popular among users overall so people forget about it all the time. LARP seems to be supported here the same way it is on RPGnet (which is to say, absolutely on-topic, but the discussion is rather low-volume and peripheral because it's only of interest to a minority of the community).