Roleblockers do not work well for both sides. Roleblockers work great for scum, but have limited use as town because you’re generally more likely to block an ally than an enemy.
At least “paranoid doctors” (i.e. protective and roleblocking both) have the advantage that the player you block can’t die. Those work well for both sides.
But a straight-up town blocker is anti-town if they use their power willy-nilly. The only information they really can get for town is if there is not kill and scum have to designate a killer and a kill doesn’t happen, they MIGHT have been the one to stop it. But in a closed game it’s going to take many days for even that to be made clear.