This measure doesn't increase spending on the homeless issue but, honestly, the San Francisco govt has shown the ability to absorb funding increases without noticeable impact in services. This is especially true of homeless services.
My impression is that this measure is born of frustration with the governmental inaction on the homeless problem in SF.
[0] http://www.sfchronicle.com/bayarea/article/S-F-spends-record... [1] http://www.sfgate.com/bayarea/article/SF-budget-increase-aim... [2] http://sfgov.org/lhcb/sites/default/files/2015%20San%20Franc...