I honestly have to clean up once I hit 5 or 6 tabs, so genuine question to those who keep many open – once you are having to search through a list, what's the advantage over just using history/bookmarks?
Finding content: History search just isn't as good as being able to preview a page to see if it's the right one.
To-do list: There's some action remaining until the tab is dismissed, or research items to compare
For bookmarks, I don’t want to have to manage a bunch of temporary bookmarks. With a tab I can just close it and move on, but if I had created a bookmark now I have to both close the tab and delete the bookmark.