It is true. If you get taken off special teams you're probably too good (a starter at your position) or you're not good enough to be on the team. Hester may not have been on a roster if he couldn't return kicks. He wasn't good at DB or WR.
It's generally where the less talented players play. Most fantasy football rosters aren't even starting people that are primary return men.
If you just running down the field to make tackle or block. Yeah you're probably a 2nd/3rd string LB or Safety or WR.
But the returners (punt/kick-off) are actually positions.