In my experience in the US people use “left”, “liberal”, “socialist” etc synonymously (and mostly pejoratively). Same for “right”, “conservative”, etc.
Maybe. A lot of people will truly believe Sierra Club to be “left” without understanding what that (used to?) mean. A descriptivist would say maybe that suggests the words’ meanings have changed.
If everyone is ignorantly incorrect maybe it’s just a different thing now.
I agree it has less utility as a word / set of words though.
>I agree it has less utility as a word / set of words though.
This is the point I think you are missing. No definitions are "changed" because there is nothing new. It is only regression. It's anti-intellectual at best. Humanity can only become more ignorant as a result. By virtue of enlightenment principles, the only acceptable way forward is to question why such a degenerate tendency has arisen and consider what to do about it.