Yes please! Firefox used to have a fantastic feature where I could crash it, and it would have a tab that contained my previous session within it. It would be there forever, between restarts and restores. I could have a kind of chain of sessions. Sometimes, I would deliberately crash the browser because there were too many, but I still had this bunch of tabs which I wanted to be nearly active. At some point, they deleted the feature - you get one chance to restore your previous session, and after that poof - gone. (I think that decision was pure evil on their part - who goes around and decides to delete a users data? And what's wrong with letting me decide how much of my drive I want to dedicate to storing open tabs? But whatever.)

The experience made me realise that what you describe is exactly what I'm trying to do. I have pages I care about. I want them findable when I get back to it, even if that means three years hence. And there are other pages which I just visited once, like a news article, or which occupied me for three weeks, like documentation for a problem I've now solved. The act of closing a tab is a communication to the web browser. I wish it would listen to it.

I could also do with a searchable, browsable list of open tabs. I was recently searching for a car. Then I bought one. So I need to go back and find all the tabs about cars and close them. I want a fully interactive window like an oldschool history window that lets me find all my open tabs about cars and close them, no matter which window they're in - unless I see that it's my car's user manual or my service schedule, in which case maybe I want to keep it open for the next five years.

On the other hand, when I learnt about % in the searchbox, it was a gamechanger. Finally I could find and reuse the tab that is open, instead of the way by default Firefox prioritises search results over open tabs.

(The other thing I would like, is something in mobile Firefox that tells me how many tabs I have open. I hate the cute infinity sign. What's the point? Because their designer couldn't handle the idea of a slightly smaller font each time an order of magnitude is exceeded? Why not let me live with the costs of my actions? Also, an easier way to manage tabs on Firefox mobile. But maybe just better tab management in general.)