since tailscale exists, why would you care about cgnat or even pay to escape it?

I'm not the only person connecting to my machines.

Some applications want to open ports and don't have the server-side infrastructure to punch a hole through NAT. Especially P2P apps and some games.

Sometimes I want to run a small, low-traffic web server from home.

Sometimes I'm connecting to my network from a machine that I don't control and can't install Tailscale on.

Tailscale uses the same range as CGNAT.

https://github.com/tailscale/tailscale/issues/12829

You shouldn't be seeing the CGNAT addresses inside your home network, should you?