Reddit certainly attempted this a few years ago. They had a 'recommended' tab in their main navigation. It worked about as well as their search at the time (ie. completely useless).

If I recall, it was based on your activity (this was pre-subreddits) so if you interacted with lots of political stories, for instance, similar political stories would be suggested.

The problem was if you downmodded a bunch of articles involving Ron Paul, your recommended links would be Ron Paul articles.

"The problem was if you downmodded a bunch of articles involving Ron Paul, your recommended links would be Ron Paul articles."

I could think of an obvious solution for that problem.

can anyone find references as to why the feature was removed?

I don't know, but I imagine the resources they needed to commit to it were pretty hefty.