why are so many cms still clinging to ancient php frameworks

half the time it feels like im digging through a junk drawer of code just to add a plugin or tweak a theme yeah wordpress is still king for a reason but even that sticks to php like its 2005. i get backwards compatibility is a thing but at what cost. honestly theres a reason modern static site generators and jamstack are gaining traction — theyre fast, secure, and dont require you to pray your host supports the right php version lowkey anyone else feel like cms devs are stuck in a time warp or am i just salty from too many late-night sql errors?