Can you recommend some resources about using Vim effectively without turning it into an IDE? I'm a self-learned Vim user and I'm sure I could learn a lot by observing experienced vim users.

Kakoune has ambitions to be the true "unix way" editor, but it makes some very questionable design decisions like plugins made in shell scripts. For the sake of compatibility. Neovim's decision to fully support Lua appeals to me much more, I mean it is a compromise but a good one. It's a good and fairly popular language.