This is not a good take. Both RSS and Delicious were immensely popular in 2004-5, and the sites that cloned Delicious (Digg and Reddit) went on to great success. There was a very active and interesting community around Delicious in the early days.

Yahoo ended up smothering Delicious because the people who oversaw it had no idea what it was for, just like they smothered Upcoming, Flickr and other acquisitions that could have grown into something remarkable.