These platforms (these meaning the ones with the most market cap) need to be advertiser-friendly in order to grow. They inherently require editorial bias.
I'm not an expert on advertising, but I suspect these concerns are often overblown. There are YouTubers who get demonetized--presumably because their content isn't "advertiser-friendly"--who still manage to get individual sponsorship deals. If these companies were serious about being a "common carrier", they would invest more money into developing an advertising market where advertisers could pick and choose the content they wanted to advertise and less money into demonetization.
Even if that’s true—which I somewhat doubt—YouTube basically makes demonetized videos disappear in terms of recommendations. They don’t admit it but every YouTuber I’ve seen get demonetized confirms that views basically stop after demonetization, aside from subscribers.
