Its not even like they indiscriminately shut down fan projects either. Just the ones that try to make money. You still have sites like Pokemon Showdown and Advance Wars By Web that have been running for several decades without incident.
That's just not true. Off the top of my head: SMBX, Pokemon Uranium, Ocarina of Time 2D, AM2R. A few years back they mass DMCA'd hundreds of fan games on the site GameJolt, none of which were monetized.
(why some fan projects like Showdown are still up is anyone's guess)
they indiscriminately shut down any sight of online smash tournaments
My friends and I made a game for Ludum Dare 36 called No Mario's Sky years ago and received a DMCA take down notice. We weren't selling it, but we still had to remove it. Maybe because Mario is 100% a Nintendo property but Pokemon and Advance Wars are co-owned with other companies.