I wouldn't consider vi usability to be overall bad. Sure, affordance ("is it easy grasp which moves i can make without affording much cognitive effort?") is terrible.

Setting up a decent environment is also a huge pain to get started with, but nowadays you can just hop into a prewarmed pool with premade setups like Normalvim or LunarVim.

But usability is not just "is it easy to learn", it's also "once i know it, how hard is it to use"

Once the moves are ingrained in your (muscle-)memory it becomes so incredibly efficient. di{, dat, yaf etc. are just the low hanging fruit, once you start with regex, macros and plugins the fun really begins.

vi isn’t usable. it sucks. but the facts are it’s installed everywhere and you can learn how to use it in 10-15 minutes. easier to patch your ignorance of basic vi than it is to install software on every machine you’ll ever edit on.