It's a pretty serious issue, and people shouldn't exploit it. I've experienced the sync/bandwidth issues and a couple of my friends who I was playing with noticed it also, and almost died because we couldn't move and zombies were nearby. I'm fairly certain it was due to the fact that I had a full pair of cargo pants inside a full hunting backpack inside a mountain backpack. I experienced the issue again when I found another hunting backpack, loaded it full, and put it in my mountain pack. All seemed well, until I tried to get something out of the hunting pack, and I couldn't perform any action for 20 minutes. Eventually gave up and logged out.

Some people might think this is cool, but it eats up bandwidth from the server and causes major issues.