What differentiates a podcast from other forms of media like YouTube is that it is delivered via RSS feeds. This lets people subscribe to the podcast using any sort of RSS reader or standards compliant podcast app.
RSS is an open source standard way subscribe to a stream of content. Sort of like a proto version of pub/sub protocol that the fediverse uses.
The reason why podcasts took off in the first place was that any mp3 player (or now days smart phone) could receive the media by subscribing to the open standards RSS feed. There was no proprietary lock in.
Mega corps obviously are not a fan of that so they try to lock people into their services regardless of this open standard. When Spotify did that exclusivity deal with Joe Rogen it was very controversial because it took the most popular podcast of the time and turned it into a proprietary media stream that you can only listen to on Spotify.