I've only used tiling window managers for over a decade, so for me screen is only for detaching, vim usually only one file at a time, and the window manager lets me tile/stack those and the web browser, zoom, etc.
The big advantage of using a single Vim instance for everything is having all my registers shared.
I can copy something into register 'a' from file One.txt, and then paste 'a' into file Twenty.txt. Same with recording macros, command history, etc.
If any of those buffers are terminals, then I can use them just like a read-only file: copy from them into registers, run macros within them, etc.
The advantage, to me, of using Vim over Tmux, is that that I don't need to remember an additional set of key chords for moving between splits and tabs, and for resizing splits, etc. Using tmux requires additional commands and key chords to memorise.
I used to love tmux before vim had `:terminal`, but since Vim got `:terminal` there's nothing I get from tmux that I don't get in a simpler and easier way from Vim.
