This is incredibly uncharitable and simplistic attack on "many on the left".
Does the mainstream “anything” care about JRE ?
He is a successful podcaster, not in the mainstream (and when he gets there he will be accused of selling out anyway)
Should CNN, MSNBC or Fox have him on as a commentator or discuss his views?
"How X makes you fat" or "Why X is more dangerous than you think" where X is something common and popular. In this case X is just Joe Rogan instead of coffee or chocolate.