I think there are a few reasons why the food in SF just isn’t as good anymore (to me):
Lack of housing and good transit between cities means you can’t hire many service staff who can’t afford to live in the city (so we don’t have late night food)
Gentrification from tech means the only way to make money in the food biz is to cater to the palates of a very specific type of person in SF
Given that there’s no room for most new immigrants in the city that they can afford, they cluster outside in other nearby cities and towns and
Well there’s no point making amazing Tanzanian or Nigerian food in SF instead of in West Oakland coz
There aren’t people who will organically like most other cuisines other than the major known ones.
Also, SF permitting is an utterly nightmarish experience I would not wish on my worst enemy (it was part of my job to try to fix it, but there is a ton of corruption that would make many of the corrupt politicians I’ve met in developing countries blush)