- History gets cleared sometimes. Bookmarks are (basically) forever.
- History includes tons of ephemeral shit, like search result pages (useless, will be different the next time you load it) and redirect pages, or things I've actively decided not to care about. If I looked at 20 shirts on a store-site but only had 3 still open, odds are good I already firmly rejected the other 17. Straight history loses the information of which ones I cared about the most.
I don't do this, but it appeals to me, as History seems to be pretty spotty, I've a couple of times recently tried to find something in my history, and it ended up as if it was never there.
It's possible to edit history, but it's easier and more useful to edit bookmarks: removing (as with history), but also tagging, annotating, and/or organising.
Heap'o'clothes on the floor vs. a well-organised bureau or closet.