This article missed the key points...
The comic book Superman looks like a bodybuilder in most of his iterations.
Henry Cavill's appearance is hugely liked by men (ideal male) plus his nerd credentials. His body is what boys admire and falsely think that girls are hugely attracted to. Boys go to the gym to hoping to get closer to that kind of body. Youtube fitness grifters have that type of body.
On how the recent Superheros have changed, they appear to be more marketed towards women and Gen Z. The Clark Kent getup for the new superman is literally wearing a haircut that only Gen Z wear. The new superman also has a body that is more geared towards what women want (not massively steroid muscles).