This is not a good idea because SDL can get fixes down the line to be more compatible with changes in desktops. I have a bunch of very old games on Linux using

This is not a good idea because SDL can get fixes down the line to be more compatible with changes in desktops. I have a bunch of very old games on Linux using SDL 1.2 and whenever they bundled their own version pretty much never works, but i can easily fix that by deleting it and letting the game use the system provided one. And TBH i'd rather games just assume SDL or is available and have it part of the system requirements (they already have other software requirements anyway), perhaps with a tiny launcher that tries to load the library dynamically and if fails it reports a more user friendly error. Most gamers on Linux will have it installed anyway since they'd be either launching from Steam (which bundles it as part of its own runtime) or also have other games installed. (sadly SDL2 breaking ABI backward compatibility with SDL1 puts a wrench to that idea, which is why personally instead of using SDL2 i just write my own code - e.g. SDL2 fullscreen mode doesn't work in many window managers)