"The fact that the few merchants willing to accept bitcoin generally convert to dollars right away suggest an underlying lack of faith in bitcoin—or at least a problem with the volatility."

Its not a lack of faith l, it's lack off trade acceptance. If merchants accept bitcoin they need to convert back to dollars because that's what their business calls for. In other words, if they could pay their bills with bitcoin, then bitcoins would flow back and forth without an issue, removing your suggestion that this is about lack of faith.