We just recently had this very discussion on a local forum. Heard the same "been doing it forever" responses despite my warnings not to.

Coincidentally I had a customer come in to the store shortly after that thread started that leaves his stainless TC encore loaded the entire season and "never had a problem" either. Aside from your personal experience being one "side effect" to not unloading the barrel, his "chamber area" looked like this below. Otherwise his barrel was spotless.