Hell the ability to access the internet via the tunnel, called Split Tunneling, is also controllable.

It’s that ability to control where the tunnel terminates that allows consumer VPNs, like Proton, to be used the way they are.

you can do the same split tunneling via proxy servers

while private individuals absolutely do use VPNs as an ersatz replacement for Proxy Servers they are nowhere near the whole use case for VPN

I agree. That also means that for certain usecases they are equivalent. It's sometimes worth checking all options to find the best one for that specific case.