Ideology is the problem. There are many who base their worldview not on reality but rather what they wish to be true.
It takes a lot to admit you were wrong, and it’s not the kind of thing I typically expect from the kind of folks well invested in ideologically driven politics.
They'll ignore mitigating factors that might not fit their narrative - things like the Reagan repeal of MHSA, the bussing of 'problem' citizenry from other states to SF, police 'quiet quitting', among countless others.
Truth is, there's plenty of blame to go around, but one side deals in bad faith because they like it to be this way because it makes them feel right.
SJF is the political ideology which local governments like SF have embraced. It's one that I personally think is to blame for many of the city's problems, and I believe moderates like myself are ever so slowly being proven right on the topic.
Also much of it is not grassroots - that's the first mistake many make viewing it as. If you look at both the Democratic Party as well as Republicans there are wealthy elites behind both, funding the campaigns. But their policies and demands can be extremely radical and populist, much more so than in Europe.
Would you consider it far-left or far-right to demand payment of $5 million to every "Black adult" (they don't define what that means), as well as eliminating all their debt AND having them pay no tax AND guaranteed annual income of at least $97,000 for 250 years AND a home in San Francisco for just $1 per family? Might sound insane but that's an actual proposal from San Fransisco, it's not a made-up example.
The same party has been in power for over 20 years. This is actually not so different from some places in Europe. In Berlin for example you can see a similar development, although maybe not with the same level of crime. But the trend is comparable.