Ah, that is because you seem to have only two tiers of tab value, worth revisiting and not. There is a middle tier of "to be considered for evaluation when I have time". THAT is what all those extra tabs are for :) The crux of course is that there is rarely time to fully look at all those tabs, so they accumulate. As you can tell, I frequently suffered from this situation. My solution was to use an RSS reader so I could just leave the potential tab unread and save all the memory (that Sam Altman is currently salivating for).

Its hoarding behavior. At least it only affects that person. Probably a sign of poor mental health, if someone can't let go of old tabs. Maybe some angry tab collector will come set me straight though.

Then it's just a mess of bookmarks instead of tabs. And maybe I was in the middle of doing something and decided that I didn't want to do it anymore right then but would eventually return to it, which could involve multiple tabs together.

But I did get an addon to help save and manage my tabs after an instance of closing my main window while having another browser window open (sometimes it's nice to pull a tab out to a seperate window so you can see two tabs at once), which would lose the full set of tabs in FF (other than the single one in the other window).

When the browser restarts, it doesn't automatically load all of those tabs until you click over to them (at least by default, I think there is a setting for it if you'd rather it did).