I’m not in the US, so that may be right. In my view this is more about how the employee feels about it: I don’t want to get into a dispute whether the half hour a day I spent on the rambling channel counts as work or not. For that it makes a significant difference if people use the channel to discuss their hobbies or whether they discuss work-related ideas. I also don’t want to miss the work-related topics just because I’m not interested in the hobby discussions.