[spenczar5]

I think there is a strong survivorship bias effect. One feature of good code is that it is easy to modify; bad code is impenetrable.

But this means bad code changes more rarely and more slowly, because it is hard. So the good code gets most of the modifications. Now, even if most of the time the modifications maintain quality, they certainly sometimes turn good code into bad code.

This is a system that gradually chews up your good code and turns it bad, until you have a big nasty mess you throw out, and start over again.