Some of it is the simple anonymity of the thousands of people who played football at some point in their life but never become famous.

Some of it is the recognition of the problem. Later in life things that we now link to CTE and such, used to just be things that happened for seemingly random or unknown reasons.

A lot of it is the accumulation of more and more hits the longer people play. That, and the likelihood of any single "big" hit increases the more impacts you take.

A lot of it is the increasing violence of the collisions as players get bigger and bigger as they age. Pee-wees aren't subject to the same forces that are NFL players

A lot of it is the increasingly absurd size of professional football players. William "The Refrigerator" Perry was an absolute freak when he entered the league in 1985 pushing 350. That wouldn't even merit a second glance today.
[Post edited by Beerman at 01/08/2018 11:30AM]