CentOS stream isn't stable, it's a rolling distro. That's like asking "why can't people running RHEL go to Arch Linux or OpenSuSE TumbleWeed?"

Oh come on, the idea that CentOS stream is on par with arch, tumbleweed, and fedora is ludicrous.

Either you don't understand what CentOS stream is, or you're being ridiculously hyperbolic.

From an infrastructure operator's point of view, there's no practical difference.