Opam documentation (update PATH, init)

I think there is some inconsistencies within the opam documentation.
For example in https://opam.ocaml.org/doc/Usage.html#opam-switch:

Don’t forget to run the advertised eval $(opam env) to update your PATH accordingly.

For a newcomer, this is uselessly painful and time consuming because he has a lot to learn nearly from scratch.

This is no more a problem for me but I had to struggle with this tool because of the official instructions (opam.ocaml.org or ocaml.org) or because of some blog posts mixing things up (using opam 1.2 vs. opam 2 commands without giving the references, etc.).

I just checked (opam 2.0.2) : I do not need to execute the command eval $(opam env): the path is automatically updated.
BTW, is it the normal, expected behavior?

About the opam init command.
I do use it, because I’m forced to. But, even if this command is rarely executed, is there an interest to do it instead of integrating within in the opam installation?