Sure, you can enable it. That doesn't solve the problem. The problem is that you cannot execute the app directly and need to use a wrapper script. steam-run and the like are hacks to get things working. They shouldn't ideally be needed, especially with a format that is meant to work without issues across distros.
And once again you don't need it for every appimage, hopefully in the near future that will be all appimages.
If you're talking about the things you linked, it seemed to me the author needs to explicitly use those. In other words, it's still entirely author-dependent whether the app will work across different distros. The list of projects that use those tools is also quite small right now. Meanwhile, pretty much every flatpak I've tried has not been an issue.