I think when there's overblown criticism (does not take into account the positive things, seeks only to paint in a negative light), that's pretty clearly FUD.
Moreover, when there's a pattern of it occurring, for at least the past 5 years...
Not saying that firefox is perfect, I have issues with its project leadership too, but its nowhere near as bad as the (most vocal) critics like to claim.
And even if it's useless that doesn't make it FUD.