It's the fact that you see an issue like homelessness and think "this is what we pay the police for", that blinds you to the actual grievances of the protestors. Instead of actually addressing issue, most Americans have developed the crutch of just calling the police who have just opted to either move the issue or throw the homeless in jail. It's sort of frustrating that on Hacker News people haven't done anymore than surface level research into the grievances behind "defund the police". A lot of their argument seems to stem to the fact that many problems they face are relegated to police (who have the funding) when things like housing and mental health services should be funded instead.
San Francisco's problem (and, I'd argue the "true" motivation behind the restorative justice) is that the city can no longer afford to in-prison more people for basic offenses. The housing problem has now extended to prisons and I believe COVID exasperated that issue as people wanted to avoid having overcrowded prisons. That plus the massively reduced city traffic has had homeless people claim a lot of open spaces. At this point I don't think funding more police departments would put a dent in the issue.