A Champion with prolonged siege range on basic attacks is still toxic, right?

I was playing Sgt. Hammer in HotS, and she has the ability to siege enemy fortifications from outside their range. She has to make herself a sitting duck in order to do this, but it allows her to prevent the enemy from turtling behind their static defenses.

In League, no Champion can outrange a turret for more than one shot, and (IIRC) only can do that with . At all other times, you have to get in the turret's range to attack it.

Would a Champion with a "siege range" mechanic be toxic design? Or could it work if it had a suitable drawback (i.e. requires immobilizing yourself)?