Ivermectin isn't popular because of Joe Rogan and he hasn't especially promoted it.

At the time that Rogan did have the episode with Dr Kory and Bret Weinstein, Ivermectin was already very popular and he hasn't been promoting it since (yes, he may have had a guest or two that brought it up during the conversation, but it was peripheral).

The media had a collective freakout because when he got Covid he mentioned on Instagram a laundry list of medicines he's taking and Ivermectin (the human form) was among them.

Blaming him or Spotify for all of society's ills is just an attempt to prevent dissent on mainstream discourse.