The many open tabs are related to states between:

1. bookmarking,

2. will look at it any minute/day now.

3. need to read/watch further when I got time.

4. page no longer available on site.

5. music to play in the background.

So what a browser mainly needs a a way of bookmarking that also stores some of the state of the page. Like position on page, selection, video/audio-position, saved to local cache.