Iirc no one except Mercurius know about Throne and what's actually going on there - it's just abstract "breaking the Ghetto" at best (and most doesn't actually even care about it and have some other goals).
Kouha describe 3 main reasons for Myoujou's defeat: time travel was used to defeat Muzan and it allowed existence of parallel dimensions; his world was constantly updating and thus allowed "bugs" that can appear with updates; he defined ignorance as evil and thus desired for unknown.