A] "It seems" is doing a lot of heavy lifting there.
B] Before the noughties, rugby was amateur, or essentially so. There were fewer collisions, between smaller people, who were less intent on dominating each collision.
C] Before the noughties, rugby was amateur, or essentially so. Players didn't earn their living by playing rugby, so there was less training, fewer domineering coaches, and fewer mortgages relying on getting back on the pitch; so whilst less was known about concussion, and there was a greater culture of "man up" there was also less urgency to return to rugby.
D] Those who were playing in the 80s and 90s (and 70s and 60s and 50s and...) were in a greater culture of "man up" and would feel massive shame about admitting something like this.
E] Those who were playing in the 70s and 80s are notably older than those playing in the 00s and 10s - to the point that, by the time the risk of memory loss was an acknowledged risk, they'd be at an age where a degree of memory loss would be considered a normal part of aging.
