If someone is launching only Vim from tmux, it possibly is an overkill.

I have stayed put with Vim, Tmux and shell, a very capable triumvirate. It allows one to build your own IDE.

Especially when your project may need some customization beyond an IDE.

Ex: I work on a python application which needs to support 4 different library versions (python wrapper over C++) and I have 4 venvs, for each version. I have a tmux session, with a pane for each venv, one vim, one tail etc. I tried for ex: PyCharm and every time I do python setup.py develop in each venv, there goes the IDE with all it's scanning stuff.

Tmux just lets me do what I want without getting in the way. And tmux-resurrect is a great addition. [1] [1]: https://news.ycombinator.com/item?id=10219003