Yeah, that's the product I am referring to. I remember when I first started using it and I thought "this is easy, there is no way this is a workout." then the next day I went to use it again and nearly faceplanted because my abs were still in serious recovery from the day before.
Of course there are back dangers with the ab-roller as well and if your gym has the type that has bands in it that assists on the "upswing," those are the best ones.
Athlean-X has a lot of haters out there and tons of people do "response" videos to his videos all the time but I think they are just trying to get a response out of him to promote their own channels. I think his supplements are BS but you don't have to buy them. I regularly look at his videos for ideas and as far as his earnings are concerned, I am sure they are immense because it appears as those his videos are made from his own private gym.
My favorite part about using those is how well it allows me to get a deep stretch. The one my gym has is cheaply made and I rarely use it.
I've watched a few response videos in the past, but I just didn't care. I enjoy watching Jeff and I learn a lot from him, so I don't need to find a reason to stop. Most are just clinging on to him for views like you said.
I really don't buy supplements at all and I usually don't follow these content creators' meal advice either. I'll continue to watch him and learn new things to try in the gym. He's lucky to have such a nice gym all to himself.