Why do people need Spotify to listen to music? There are numerous other platforms.
In the same way, you don’t need Spotify to listen to Joe Rogan.
If you want to listen to ALL of Rogan’s podcasts then you do need Spotify. Excerpts are cross-posted on other services by fans and those are subject to being taken down on a fact-check basis. So Rogan’s presence on other services is informal and shot full of holes.