Bookmarks should include the date they were added, so years later people can more easily identify and remove old bookmarks

I have had the same browser profile for SO many years, and my bookmarks have been imported from browser into browser into browser, going back decades.

I decided I wanted to clean up my bookmarks, and I realized how nice it would be to be able to see the dates bookmarks were added, so that I could sort by date and start clearing out the oldest ones first.

Actually good idea. However that could leak a lot of Info about you,

That is they did this you would need to collect a lot of data and make it less private.

So that i would recommend this as a optional choice.