Having hundreds or thousands open tabs also confuses me and always seems like a mess to me.
The way i work: I mostly work on a one thing at a time. For that i can have probably at max 40 tabs open. Once it gets past some threshold(i don't recognize or remember what's in them) i tend to start to close the obsolete ones. If there is something i find useful i bookmark it. If there is something i think i would like to read in future i also bookmark it. Once the work is done i close all the tabs. In general i like my tabs closed, it brings peace to my mind.
My thoughts on this kind of thing aren't in any way backed by studies or research (I know some folks are sticklers for that sort of thing), but they essentially boil down to reflecting on human history.
The ability to store a huge amount of information and near-instantly recall it with these computery things we all love is an incredibly new development that I don't really consider compatible with my brain. If the brain is a somewhat general purpose computer that's been really slowly optimised by evolution, the alternative approach to ours is akin to* scheduling hundreds of threads on a small number of hardware threads. Doable? Sure. Ideal? Doesn't feel like it to me.
I've tried allowing myself to just continuously spawn tabs and it makes me uncomfortable much like it does to see a Windows desktop used as a dumping ground for whatever a person happens to want to save on their machine. Fortunately I almost never see the latter these days, and I'll choose to believe people don't do that anymore without verifying that assumption...
I don't think I go into thousands, but easily accumulate a few 100 tabs. The way I work, I rarely have a task truly done in one go. Besides various side projects, I work on multiple websites for multiple clients and constantly need to put one on hold and wait for feedback, so I go work on another one. If I expect feedback withing a ~2 day period, it really doesn't make sense for me to close the related tabs. Not only does it save time when picking up the task again, but helps me reconstruct my train of thought without having to take notes.
The way I think of it is kind of like swap memory. Instead of wasting effort saving to disk and verifying the saved data (taking notes), I chuck the data somewhere it isn't in the way (a new virtual desktop) so I can pick it up later. In fact, this is exactly what happens with the tabs at the system level. Since I'm constantly running out of ram and have a stupid amount of swap space set up, my OS gladly swaps the relevant browser processes and unswap the relevant set.
The way i work: I mostly work on a one thing at a time. For that i can have probably at max 40 tabs open. Once it gets past some threshold(i don't recognize or remember what's in them) i tend to start to close the obsolete ones. If there is something i find useful i bookmark it. If there is something i think i would like to read in future i also bookmark it. Once the work is done i close all the tabs. In general i like my tabs closed, it brings peace to my mind.