If they can lift 5000 to 20000 sand bags they can try. That and roadway concrete barriers are what they are using to plug the breaches.
Like I said, what's wrong with human-sized sand bags? Just because they are using huge ones doesn't mean they can't ALSO use little ones. Now that the water level has stabilized, they aren't fighting the current (which was the purpose of the huge ones).
Point being: Every little bit helps. And it's sure ALOT better to be part of the solution than to be part of the problem.