I don't think they had a good product manager. I quit delicious a few months ago because of their lack of support of browser add-ons. It takes less than one week to develop a good add-on for Chrome!

Another disturbing thing was the UX: delicious was slower in 2013 than in 2009...

Sorry, I can only bash them: it is hard to do a business around Delicious but destroying what worked is irrational. The delicious app for Android goes in the right direction but it's late.