Having one sponsor like Spotify means you get paid but also retain a lot of freedom and distance from the audience. If I was a podcaster I'd much rather take that route, even if I lost some listeners.
I'm not sure I understand the "yet" here. Freedom of speech protects the ability to say things but has few implications on the incentives for saying things. It seems to frequently be cited as a variety of different things that are tangentially related to public discourse. Anyway, I'd hardly expect people in the 18th century to come up with a comprehensive framework for protecting against media outlets depending on corporate interests to monetize, if that's your concern.
Perhaps that's because I'm selecting content with little political or controversial content. But even there, I suspect that people who do want that content will find that the advertisers who want them are the ones who naturally appeal to them anyway.
Consumerism in general is always insidious, but that's hardly limited to podcasting. There are a lot of paradoxes associated with being wealthy enough to be in an advertiser's demographic, and yet still be vulnerable to wanting something to make you happy.
The US values free speech very much, yet for some reason you will have a hard time to find any podcast who isn't dependend on or tied to some coporate interest (and be it the Nord VPN thing they are selling).
I am btw. willing to throw money their way, as I do with other podcasts. But the option wasn't there to begin with.