To me they're completely different purposes. Tabs are short term - for whatever you're working on right now. It's like a short-term cache, a worktable to keep everything in your head right now easily accessible.
Bookmarks are long term, like a filing cabinet. You may not be using it today, but you want to hold onto it for later.
If I had to use either one for the other purpose, it would suck.
I pulled up an old bookmark file that I had backed up on CD-R and pretty much every single link was dead. So at best, it was just a memory of something that I thought was worth saving at one point and might go back to someday. So more like what you said: "history of things I've found that are interesting" but not being able to use them to get the website (unless it's in Wayback Machine perhaps).
Bookmarks alone don't quite do it because stuff is moved or dies. A saved copy of the webpage does do it, though, along with the bookmark. SingleFile is a godsend here. I also really like Shiori and other similar bookmark managers that snapshot the webpage along with the bookmark. Even if the saved copy is incomplete or not high-fidelity, it's often enough.
And given how dynamic and interconnected content on websites can be, I don't see a lot of use for snapshots - too much would be missing from a snapshot. Could be nice for an in-case-of-emergencies though, at least you've got something.
So we file it away to relieve that mental stress. We now have the option to retrieve it should it ever become necessary, but we probably won’t.
I find the same thing to be true of note-taking and storage units.
Now we just need it to save the page state like it would for an unloaded tab. But I guess the hard parts of that aren't really implemented after all, all kinds of issues though with serializing the page state, making it work with sync across platforms, or just dealing with someone trying to open the same state multiple times...
At the very least, I personally need tags. Tree hierarchies are too limiting, but tags allow adding free-form metadata which can be used to quickly find anything. I often don't remember the actual URL or title of a web site, but I'm looking for a general category, and with tags I'm usually able to find what I'm looking for. This does require a certain level of discipline from the user to use tags consistently, but they work well IME.
These days with ML tools it's easier than ever to assign relevant tags to URLs automatically, though I would personally not rely on them because of their propensity to hallucinate and not follow conventions.
And, like you say, web sites change and disappear constantly, so snapshots are important as well.
I've been meaning to try SingleFile/ArchiveBox/Wallabag for months now, but I'm currently too comfortable with Pinboard. Pinboard has been working great for me for many years, contrary to the negative buzz around it, but I don't have confidence that it will stick around forever. I just hope that I can export and migrate all my snapshot data as well...
For long-form content that I want to come back and read later, I find Wallabag is quite good. For making snapshots of large websites I use Kiwix.
I'm trying out using the Obsidian Web Clipper extension, which essentially does this (and using it for anything I'd previously have bookmarked).
I've been using Zotero for that, but I again wish we had a browser maker that was concerned about users, and felt their only goal was to give the user as much control and ability as they can handle, and as much protection as they ask for.
Sadly, Zotero and a lot of other software in that line is built with no thought to speed, I think more than a few thousand entries will make it impossible to open, browse, or search. This seems to be a commonality of all of this type of software; that it isn't really meant to be used.
Logseq, etc, are tools that help facilitate this, albeit in not plain text format, but close.
Being able to save a page also seems to be against the interests of publishers now - they would rather you revisit the page than have a copy. Substack for example seems to try to block the web clipper because you could clip paid articles and read them after your subscription lapses.
I hate it when (news) articles change without acknowledging the changes.
Edit: come to think of it, MediaWiki + a crawler bot would be near ideal for this.