"Just" that. But the reality is that if I'm looking for a commercially licensed photograph, font, or whatever, there are already plenty of sites that I can go to and pay for. And, if I'm looking for something free in a situation that clearly doesn't fall under non-commercial (e.g. marketing materials), I'm just going to skip over anything with a "non-commercial" only license and pick something else.

'Just' - but many need to do that through a legal department, so that requirement would be a dead stop unless there was an extreme advantage gained vs alternatives.