The difference here is that tabs capture intention whereas history captures everything. A page remains in a tab because you opened it and didn't choose to close it; that's a signal. Example - if you are trying to find something elusive, you might end up opening a dozen blogspam pages in tabs and then closing them immediately because once you see them they're obviously useless. They are now gone from the tabs. By contrast the history will remember them forever and show you them, even though you don't care.

I use them as favourites rather than nostalgia, so even I think this use case is kinda crazy, but I get it. Tabs work really nicely without deliberate thought, you don't have to choose to save things, you don't have to choose to dismiss things, stuff you were at least vaguely interested in just sort of accumulates effortlessly as you use the browser in a natural way. There may be something browsers could offer to do this better, but it would be a hard problem.

Great point. Maybe history should capture time spent on page (with page visible) and allow you to filter and sort by that.

This won't help with pages that you thought were interesting, but got interrupted by something else immediately.

Time viewed before closing the page could be a metric though.

The browser history worked fine while the web still was rather static. Not so much now with dynamically generated pages where the content changes for better ..or worse. A tab, in contrast, keeps its state. There are tools, such as SingleFile, Zotero, Pocket, screenshot, "print/save" to PDF etc.. but depending on content, an open tab is convenient enough.

Do tabs that are unloaded keep much state? My understanding was that they basically loaded as if a fresh navigation except for some extra form field preservation.

Or is the active state serialized to disk somehow?

Not much state is kept: maybe about as much as if you were to navigate to the page again with the back button (which is an annoyingly little nowadays).

It would be interesting to explore a UX that blended the two: history certainly feels unreliable, and the search is worse as well as fewer tools to organise it.