If I visit HN, browse a bunch of comment threads, and find something I want to come back to later, that's 1 tab but 20 history entries.
Same if I searched for something on Google and eventually found something I want to come back to later. Except that's 1 tab and 50 history entries.
To recover that state via history is practically impossible. It's a needle in a haystack. I've occasionally needed to do it, and it takes a long time.
(Compared with a tab, a bookmark doesn't work well either for something to come back to. Anything where there is a context, such as scroll position. Perhaps if bookmarks were better, keeping track of scroll position and allowing text to be highlighted or a note to be attached, and showing a thumbnail (scrolled to the right place), and retaining some temporal relationships between different pages. But I find bookmarks consisting of just a title and URL to be completely useless.)