@evan Spam and harassment also existed in email, at orders of magnitude greater levels, and yet Google did not try to kill open email standards but simply solved the issue.
They rolled out Gmail on April 1, 2004, with a good spam checker that improved over time, and didn't get into XMPP until much later.
You present no evidence of the claim that "spam and harassment outweighed the benefits". No evidence appears to exist except a single press release, bereft of even a single number.
Skeptical.