Just to finish up for now, the provably fair system is simply perfect, even I cant come up with a better system, so, no doubts here, the problem is how its used in combination with other factors
That's not what you said before.
please read again, specially the EVEN part
how they can cheat even using provably fair system
Provably fair means you can prove to yourself that it is fair. It is not possible to cheat that system. Or to put it another way, you are talking bullshit.