"Incredibly useful" would imply that if you told me about Twitter, I wouldn't believe you. As much as I wish it were otherwise, it's not that hard to believe that someone invented IRC over HTTP and gave it a silly name.
Did you understand what the GP meant? Yes. Did you need to point out to the world your complete mastery of the English language? No.
The GP's point was that Twitter is useful, despite it's relatively low score on "innovative new technology" scale.
I'm still skeptical and I have used it.
Of course, that woudl imply that the act of removing credibility from something would be "decrediblizaiton" or "decredencing".