I've only lived in San Francisco for two years, but I'm catching on that the mindset here is "chase the exit" not "delight the customer" (failing to realize how much more likely the latter makes the former). With that mindset the state of code quality is not surprising.
There are some seemingly practical outcomes from this. One of which is a bias toward fast features, leveraging frameworks, and little time spent "doing the dishes." Because, honestly, if 7/8 of your startups are going to fail, you only have to spend the time/money to clean up 1/8.
A problem with this "practical" mindset is that the skills required to remove complexity from a system are significantly more refined and harder to come by than the skills needed to keep a system simple in the first place.
I may expand on this later, but I'm interested in others thoughts and observations.