Vim is not really an editor. It is a way to edit text, you can use vim in almost any environment. You are also totally wrong about vim or emacs not having code completion, that is just nonsense.

I use (a version of) visual studio, the first thing that I did was installing a vim extension.

Also vim itself already supports almost any of these features with some basic plugins for the completion logic. If I type "." in my vim I get the same thing I would in visual studio. If you are saying "vim is bad because it lacks X IDE feature" you are missing the point.