1) The scoring rate during Beliveau's career was literally identical to Crosby's. During both of their careers, the league has averaged exactly 2.85 goals per team, per game.
2)
Beliveau's best scoring finishes: 1, 2, 3, 3, 3, 3, 4, 6, 8, 8, 9
Crosby's best scoring finishes: 1, 1, 2, 2, 3, 3, 3, 3, 5, 6, 10
3)
Beliveau's per-game scoring: 1, 1, 1, 2, 2, 2, 2, 3, 3, 6, 7, 9
Crosby's per-game scoring: 1, 1, 1, 1, 1, 2, 2, 3, 3, 4, 5, 6
So we can level the playing field three different ways (one of which is the fact that the playing field actually is level)... and all three ways confirm Crosby as the superior scorer.
And then the crucial piece of context that un-levels the field: Beliveau achieved these numbers while playing with the league's top-scoring defenseman AND the top goal-scoring RW of all time to that point. Crosby did it while competing for opportunities with a Hart-winning 2C.