Why don't critical rates mean anything anymore?

I think crit hardcaps at around 95%. A friend had Dice 4, CO'd SE, crit ring and 8% critical potential. His crit range read 79%, with CO'ed Cannon he should've hit 100% crit, but still reported seeing non-crits.

There's no crit cap. In fact, you can even go over 100% critical hit rate.