Tiny is relative. Here's Joe[0] - he looks more-or-less like a diet/exercise fitness enthusiast in their 20s, which seems in line for his message/goal of "hey I'm just trying to hold on to that for as long as possible".
Here's The Rock[1] at 48 years old. You can search for in-role Ryan Reynolds, Chris Hemsworth, Henry Cavill, etc, etc - Joe is tiny by comparison and all of these actors seem to get bigger and bigger as they age (look at any of them from roles 10 years ago) - which is the exact opposite of what happens to men as they age.
Here's an example[2] of what they look like (in "Hollywood" shape, but normal for age) when not tuned-up to the max on whatever they do/take for these roles.
You're right, Rogan is smaller than I remembered him being. Indeed, I'm not entirely sure why he's taking any gear, doesn't seem necessary to maintain that sort of body.
On the getting bigger thing, muscle is cumulative as long as you keep exercising it. I have always assumed The Rock was on gear while wrestling (although he had a great frame to begin with) but I don't find it odd that he can maintain that at 48.
On the getting bigger thing, muscle is cumulative as long as you keep exercising it. I have always assumed The Rock was on gear while wrestling (although he had a great frame to begin with) but I don't find it odd that he can maintain that at 48.