That's true, the two concepts shouldn't be conflated.
But, that said, if you look at the ratios of guests he's had one, what would you estimate the ratio of "wackos":"credible" has been?
He's had a few of the former on there obviously, but he's also had nearly a thousand guests. The overwhelming majority have been credible with regards to the subject matter they happened to be covering when I scan through his guest list.
Joe Rogan Podcast Guests - JRE Podcast
...and it's highly doubtful that his show ever would've become as popular as it did if he didn't at least know how to conduct a halfway decent interview with people.