My guess is they underestimate the scale at which it's used in most businesses who do and the relative unimportance of the accuracy of the data it holds. It's never going to perfectly capture all details of work because of its inflexibility, but it's better than nothing or not even trying. As long as everyone understands that and nobody is delusionally running around with a trusty clipboard and a whip or rallying for significant change based on it without consulting the people actually entering the data, it's alright.

There's a lot to keep track of. Definitely not my cup of tea either, but it is what it is.