That's what everyone says whenever this subject comes up. It always gets a big laugh on the anti-radio boards. If you go to all the threads about stations speeding up songs, that's the theory. They're speeding up songs to squeeze more commercials into an hour. But if you read the financials at all these companies, you see a very different story.
These radio companies don't have an over-supply of advertisers right now. If anything, there's a shortage. They're talking about CUTTING commercials because there isn't enough advertising to fill the entire day. That's especially true in the evenings, weekends, and overnights. But it's also a problem in mid-days. So it may be popular to blame corporate for this, but the facts don't bear that out. There's a shortage of advertising, and that's why they're laying people off. Because that's the other side of the advertising coin. If there was so much money pouring into these radio stations, they wouldn't be laying people off. That also goes for Sirius, Spotify, and even NPR. That's one of the reasons why these companies keep selling their stations to religious groups. They're the only ones now with money.
The other thing is that the DJs really don't know where the music comes from, other than it's loaded in the automation system. That's the extent of their involvement.