My point was that the size/speed/strength factor in the current game is offset by the current rules. Guys still get whacked in the head, perhaps with more force, but less frequently.
And if it does turn out that CTE risk is confirmed as equal to or higher with repeated sub-concussive impacts vs. a series of concussions, then I would conclude that the players of yore were more at risk. Why wouldn't we have heard about them? Because without study and acknowledgement of the risks they would have suffered in the shadows.
I remember reading some years ago that the average life expectancy of ex-NFL players was somewhere in the high-50's years of age, well below the general male population. The reason conjectured, without a study of causes, was that upon retirement their muscle turned to fat. That would be a convenient explanation that exempts the inherent violence in the game.