This is reasonable enough, but personally I'm not really convinced a text editor should be handling windows at all, especially since neovim allegedly is designe

This is reasonable enough, but personally I'm not really convinced a text editor should be handling windows at all, especially since neovim allegedly is designed to be embedded by a ‘real’ UI (and presumably could be embedded by a terminal-based UI that handles windows—or just uses tmux). I do recognize that I prefer software to be simpler than most people (for the record, much of the time I use ed(1)).