The entire thread in Kiel’s first link is an interesting read: A case for postponing ABI stability - #46 by Chris_Lattner. It seems many of these issues were thrashed out two years ago and to an extent the arguments still apply today on both sides. I’m putting forward more of a third way that gives you the best of both worlds but it’ll be difficult to change course now. As I say, it can be adopted later if need be.