[Asooka]

Qt can trivially offer a C ABI if they want. Glib can't be type safe no matter how hard they try. People don't seem to have any trouble making Qt bindings for languages like Go, Python, Java, all of which you could say strongly prefer interop with C. Part of the reason is that Qt is written in a way that avoids use of more exotic features and templates for most things. MOC could be replaced by template magic nowadays, but I don't see any value in doing so - you will just make compilation slower and bindings with other languages harder.