I think that fact needs some details.
If you rarely reach A+, A or B on 14* titans of course C will give you a better Loot.
I almost never finish C and the few times I did that - Loot was crap. Does that mean C is crappy for everyone? No.
Do I get a lot of 4* mats on A+, A and B? No. But do I count on all my team-mates to do their best and not go for C when they could have made it to higher damage? U bet.
I’m just tired of hearing that C is so much better Loot. If all players in an alliance go for C - The titans won’t die.
Not wanting to reveal the details about Loot just convinces me that I need to be okay with all my team-mates effort when stacking 14*.