Joe Rogan doesn't need to do these things if he's just "hanging out with his buddies smoke'n" but he also doesn't have an obligation to have provocateurs and hacks like robert malone or ben shapiro on his show. He does it because he knows his fanbase will listen to it, ingest the information, and then speak it as fact to their friends and family - and THAT is where the danger comes in. Furthermore, he also knows that parts of his fanbase will go wild to see their fringe views espoused by a guest on their favorite podcast, without Joe challenging them to back their claims up with facts. I'm sure he also knows that his listeners skew young and male, and impressionable young men have been radicalized to a dangerous degree on the internet. Having the same views on his podcast as conspiracy theory sites, for example, will undoubtedly make it easier for the bad actors running these sites to radicalize JRE listeners (who will then, of course, become a part of the fanbase that loves when their theories are given time on his show in some perverse feedback loop).
He has also inked a deal with the largest music streaming service in the world for more money than any of us will see in our entire lives - at that point I don't think you can even say he's just "hanging out" any more. It's facetious at best, and wilfully negligent at worst, to assume that no one thinks of him as an authority figure, because even if he's playing the everyman character his guests profess to be authority figures in their fields. If he doesn't seriously challenge their false claims or ask for evidence from credible sources, he's doing his listeners a disservice.