Yeah, active Pinboard user as well, coming from del.icio.us a number of years ago. Have 35,549 bookmarks in Pinboard as of right now, will almost certainly be a bit higher by the end of the day. Definitely a personal knowledge repository. I can't tell you how many times I'll be talking to someone and say, "You know, I read an article about that a few months back... let me send you the link" - really useful. I also like when I save a really good link and see that others have linked it too, and then I can explore what else those folks have bookmarked with that same tag; it's a great way to find other high-quality pages. Kind of "social bookmarking" :)
I think you're right. However, personally, I can - 95% of the time - remember a few words from the page that allows me to search it on Google. 95% is conservative figure. I honestly don't remember the last time I couldn't find something. Might have been a year ago. Furthermore, it's usually much more accurate to simply search your own browse history. Granted, one might need to delete the history or that can get large, but I usually only need to search for something within a year of the last retrieval.
One thing I've learned from running a bookmarking site is that people have vastly different experiences and practices with re-finding stuff online, which sometimes makes it hard not to talk past one another. It turns out the way we remember, find, and re-find stuff is very idiosyncratic, and the success of it depends a lot on the subject domain.
