"The time, patience and level of enthusiasm required to learn the craft to the level you can develop a piece of software that is well-designed, performant, easy to reason about and an overall joy to work with is about 10 to 100x what the average engineer is willing to put in."
It's not just that, but the typical company is too busy chasing new features and fighting fires with understaffed engineering teams on constant death marches to unrealistic deadlines. Nobody has time to do things right, though many of us want to. Instead the systems accrete endless layers of bandaids and half-assed solutions which everybody hates but no one has the luxury to fix or solve properly the first time.