Writing has been on the wall for some time. Surprised anyone that uses Delicious seriously did not switch to Pinboard or equivalent. No sure Avos is to blame so much as delicious users not being proactive about the inevitable.
The reaction of Delicious users is a product of poor communication on behalf of AVOS. They wanted it to sound like they were simply taking the reigns when, in fact, they were building a new product. Nothing from this email indicates that the old delicious is going away:
"Dear Delicious User,
This is our final notice to let you know that Delicious is transitioning to a new owner, AVOS. To continue using Delicious, you must agree to let Yahoo! transfer your bookmarks and Delicious account information to AVOS by September 23, 2011. After your bookmarks and account information have been transferred, you will be subject to the AVOS terms of service and privacy policy."
That read so much like an ultimatum (and was honestly the first email from them that I actually saw about the transition) that I had little desire to migrate since I had already moved to Pinboard. Kind of like if Facebook sent something similar...meh, just dump me already, my life exists outside your free service.