Exactly. I cannot comprehend people with dozens of windows with thousands of them. How do you find literally anything at that point?
I usually close all, sometimes if I start a long video I'll keep it open and paused until I come back to watch more of it. But that's just one, and just because that site won't remember where I left off, and I don't want to memorize what the timestamp is. I will have to refresh the page to get it to resume loading the video, but I can remember the timestamp for the 2 seconds it takes to reload and click back to it. But I'll forget if I have to come back hours later.
I got so used to the Safari tab system that I decided to replicate it in Firefox (recently switched).
For me Three Styles Tabs and Simple Tabs Groups have helped me enormously to keep track of all of my tabs, additionally, I think you can search your tabs within the search section.
As almost all crap I have, I keep categories/groups of it:
Bookmarks/favorites are designed specifically for managing large collections of more or less frequently accessed sites. They have descriptions, tags, folder structures, etc all built in and requiring a few kb of disk space each instead of 100MB of RAM. I'm wracking my brain for a reason why deliberately keeping hundreds or thousands of tabs loaded could possibly be more effective at managing a collection of resources. I got nothing though...
On linux, with kde, there is usually a browser extension preinstalled called plasma integration.
It makes it so that when you search from the KDE equivalent of window's start menu, you can also search open browser tabs or history.
I close all tabs once I'm done, but when trying to solve a programming/devops related problem, having lots of tabs open lets me see more than one approach to a problem, along with opinions, side by side.
And research in general requires a lot of tabs, in my experience.