This is because it is what other clubs do/have done. We are copying, or trying to copy, what others have done successfully previously, always a few steps behind.
We have nothing original going on here - like, say, Brentford with their approach; or Brighton; or Swansea a few years back - just pale imitation. Nothing original other than the Bristol Sport umbrella/group thing, which doesn't appear to have helped City to any great degree, and nobody else in football as far as I can think have so far chosen to copy.