Totally depends what field you're in. Healthcare is a field heavily driven by credentials and people put all kinds of shit behind their names, but even here, some folks do get carried away. I mean, if you have a master's in nursing (MSN) there's really no need to tell us you have a bachelor's in nursing (BSN) as you are not getting the former without the latter. Then again, we're talking mostly nurses that over do it, and most of them are silly people to begin with.
However, knowing a doc is a board certified pediatrician vs. a board certified geriatrician actually gives useful info.