like every rule, there are exceptions and room for common sense. In one particular instance on a busy river, there channel is 40 feet wide at best. Anchors generally don't hold well, so most fisherman have a trolling motor/kicker to hold their position. (so they are NOT at anchor, they are under command)
Anyway, it isn't uncommon to have this area clogged up enough that it is tough to even get through. The fishermen tend to forget there are other boaters and do this intentionally... At that point, it just escalates the situation and nobody bothers slowing down anymore. (including other fishermen!)
So no, i'm not saying they had it coming, and I still do everything to minimize my wake. There is no danger to anyone involved other than a couple drops of their beer spilled, and I maintain as much separation as possible.