To me it appears to be quite a display of cognitive dissonance.
"We (wikipedia in the aggregate) don't think that credentials carry any weight. At least, not enough to influence our content or policies in any meaningful way. However, because other people value credentials, we have trouble building credibility without them, so we would like to advertise them in order to enhance our reputation. We're happy to trumpet our contributor's qualifications, as long as it's clear that they mean nothing to us and in no way affect our process."
Jimmy Wales wrote:
Such an initiative would have to be done carefully in order to respect our (fairly anti-credentialist) culture. First, anyone who ever suggests that a credential gives one precedence in editing gets a bonk in the head with a WikiClueStick.