I said this in a sibling comment but, there are also plenty of examples of feature requests that were not rejected:
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests?state...
https://gitlab.gnome.org/GNOME/gtk/-/merge_requests?state=me...
If you're going to look at the pattern of historically rejected requests, please also consider looking at the pattern of requests that were accepted.
If you'd like, I can give you a more thorough explanation as to what is actually happening in any of those issues you've linked.