in some cases no particular individual are able to see something's wrong, and only someone with a general overview of the system can see the pb. in this case,

in some cases no particular individual are able to see something's wrong, and only someone with a general overview of the system can see the pb. in this case, every single individual in the chain ( from backend dev to frontend dev to tester to enduser) are able to see that something's very wrong. Which means none of those people are competent. Not any of them.