These are my thoughts on the anticheat, having gone through hundreds of ban disputes and even seeing it ban some of my friends.
As people said, nothing can be 100% accurate. However, the anticheat is extremely close to it. Almost every single person that has been banned by it has admitted to hacking in their dispute and apologized for it. Not only that, several high profile players have made ban disputes, denied having hacked in the first one, and then after taking the forgiveness route after realizing that just denying using hacks would not get them unbanned.
I can say that the people that say they were just "walking around and then got banned" or they had just "killed this player and then got banned" are not providing the entire story. The devs have taken into account several situations that could lead to the anticheat falsely banning people and have eliminated those.
If you or a friend of yours strongly believes that they were banned unfairly by the anticheat here my is my best advice to you - provide every single detail about the game that you can remember up until you got banned. Any information that you can provide us helps.