Well, one thing is that I have significantly less tabs than I had bookmarks. My bookmarks where somewhere high in the 5-figure range, maybe even 6 figure.
My heaviest used system has less than 10k tabs open.
It’s not ideal, but the tab trees in treestyle tabs mean I usually can just scroll a short bit and click to find what I need.
Ideal would be a fully external bookmark manager - but browsers don’t have APIs for that, so you’d have to end up writing an extension just to talk to your external management solution, and since they gimped the firefox plugin system about a decade ago you don’t really have any useful APIs for doing that. (I’m current maintainer of the emacs keybindings extension for firefox, it’s a hot mess to get a fraction of the functionality that was possible with the old extension system working. No idea why they don’t offer the ability to do custom keybindings)
Just like the UK exemptions most of those were given to early members as rules changed to get them to agree to the rule changes.
New members don’t get that - and UK would be treated like a new member.