I am one of those that keep lots of tabs open. The main reason is that I expect to come back to the page later, so I don't want to close the tab. This is really a job for bookmarks, but they are much more cumbersome than opening or closing a tab. My current solution is to use a tab group plugin.
The good solution would be to integrate tab groups and bookmark folders. A tab group could simply be a view of a bookmark folder. Switching what bookmark folder I view is the same as switching tab groups. It needs to be fast though, and it needs to save favicons and tab title, because when you have many tabs open, favicons matter. Then all the synchronization, backup and organizational tools for bookmarks can be used for my tab groups!