Unfortunately most of game developers that decide against use of SDL2 do that based on their experience of Windows development where it's pretty much standard to have own code for everything (except development tools and some middleware). E.g they think that their own code going to take less lines and be cleaner than SDL.
As result these people usually don't even consider any alternatives as all of them even worse from their standpoint.
As result these people usually don't even consider any alternatives as all of them even worse from their standpoint.