[Walt.]

Every time this subject comes up it veers into the "what if..." world with lots of reasons for the no seat saving rule not be be enforced.
By this logic nobody should ever stop shoplifters. What if they have a gun? What if they have a starving baby at home? What if they accidentally put the item in their pocket and aren't really stealing?

Personally, I have no problem with 2-cushion savers. It's the whole roped off 6-12 seat sections that get me.
Anyway... after announcement one half-hour before show time just have the on-site staff (who are already there) gather up ropes and tapes. Do this a few times and it will stop.