Hazel doesn't close tabs because it's 'like a trip down memory lane.' Mozilla says it has some profile and tab group features coming later this year that might help her organize those memories.
A lot of things stay open and I might lose touch for sure.
But I have a lot of "per window" tab groups about specific work subjects, specific technologies, specific subjects of interest. A lot of it stays open until I look into it, which sometimes can take a while
Nobody actually looks at bookmarks, or at least I don't. Bookmarks are where I dump tabs that I should look at, but probably won't, but want to clean up tabs.
I have a few hundred bookmarks, but I don't think I've actually looked at any. I usually get around to looking at my open tabs though.
That said, I generally cap out around 200 open tabs, and then I'll cut it down to 10 or so essential tabs. This happens almost weekly. "Close to the right" and "shift click" to select multiple tabs are amazing.
I use bookmarks, but I don't group them into folders. Instead, I add multiple keywords/tags. I don't really use them by going to the bookmark menu. I rely on them showing up in the search recommendations when I am searching for something.
Granted I'm guilty of saving some open pages as bookmarks and only getting back to them 5 years or so later. But generally if you're organized enough bookmarks should fill that space pretty well.
I use a tab manager, and a tab killer that kills the process while not actively in use to save resources. I believe the tab killer is auto tab discard, and the tab manager I can't remember which it is right now