It's probably more or less true, but I wouldn't assume it's a total black-and-white situation. Commercial endeavors are run and controlled by fatcats who don't want to rock the economic boat/challenge the establishment because it's working out well for them. But there may be scenarios where they don't care, all they care about is getting a share of the artist's profits, or even scenarios where they're willing to entertain revolutionary ideas because people like them which means they're profitable. But the latter case could be tainted by some sort of filtering of exactly what ideas are acceptable. And also commercial sources may want to filter the art for things that could get them into legal trouble. Like the FBI once raided a Rage Against the Machine forum and shut it down.

anyway, these are my opinions on what's likely without really having any experience or reading about the subject.