I can’t really tell what benefits there are for being exclusive.
As for legacy sites, the ones I’ve sampled caused me extreme psychic and spiritual pain.
The reason flightsim.to has soared is because of its interface. And that interface has also made it a lot more fun for creators by interacting with users, responding to requests, seeing what they do with your mod and measuring stats etc.
Uploading to some grey cliff slab designed in 1999 and never hearing a peep again isn’t going to encourage people to keep the content coming.