I think the best way to compare the two is imagining them dropped as rookies into the same situation…
Cam with a franchise that valued protecting the quarterback and surrounding him with weapons?
Allen with a franchise that rolled out Byron Bell and Matt Kalil as the cornerstones for protection? Devin Funchess and Kelvin Benjamin, Philly Brown, Brenton Bersin?
They’re both great players; Cam was just so physically dominant, and Rivera so locked into the stoneage of NFL philosophy, that Cam was the crutch that covered so many weaknesses.
In today’s game, if I’m starting a franchise with either a rookie Allen or a rookie Cam, I’m taking Cam 100 out of 100 times. Allen is a great great player but with a competent franchise Cam could have been up there in the goat discussion.