It's as the other commenter says. This is just a story you told yourself to justify your opinion after the fact. X11 is ancient and its sprawling patchwork codebase shows it.
Despite being ancient it's still better than Wayland. The "same developers" narrative is just a story you tell yourself to justify your opinion after the fact. Wayland is fundamentaly flawed on every level. Its sprawling patchwork of parallel infrastructure an duplicated effort shows it.