I also use the basic HTML view on desktop because 1) I don't want to leave the tab open with the modern UI since it inevitably uses up over a GB of ram by itself and 2) I don't want to close and reopen the tab with the modern UI since it takes O(10)s of seconds to be responsive.

I remember getting access to gmail when it was in the invite-only phase and thinking that it was absolute magic, that this was the future, and that I'd never use anything else. It only took a huge pile of JS to undo that. I use basic HTML now for gmail and I've switched a lot of what I do to fastmail.