How are we measuring that? Firstly, as a nitpick, the mainstream media these days is Russel Brand. He has an audience comparable to a group like CNN. Possibly slightly larger.
Secondly, the quality of the podcasters is generally better on net than the big media companies. They tend not to be gung-ho all-weather war supporters for example. People like Brand might get a lot of details wrong but have more coherent takes on big issues.
Thirdly, and related to secondly, the podcasters tend to take less money from big entrenched interests in the military-industrial complex or big pharma. They rely less on being spoon fed access to powerful people. It is easier to follow their incentives and style than work out what a media company is trying to push this week.