@TimetheYoutuber. Incompetence of some developers has caused this. But I am not saying that all Ethereum developers and contributors are incompetent, some of them are the best in the cryptospace. The problem with some of them is they know the project is no good but they remain to keep silent.
I wouldn't say they are "incompetent" but I think there is work that needs to be done, that is for sure.
So what would you call the developers who are at fault for the vulnerability that has led to millions of dollars of ETH being trapped? I reckon there is no other word for it but
incompetence. Also remember that there was another Parity hack last July that allowed a hacker to steal 150,000 ETH.