This is a heavy mischaracterization of Progressives. When it's 100% unit that are below market rate, it gets blocked. When it's 50% BMR, it gets blocked. When it's 20%, it gets blocked.

This is because the true position of Progressives is that any development has a chance to cause harm, and they prefer the current situation to any harm, in a messed up form of the trolley problem.

I would also urge you to capitalize the P, as the Progressive positions in SF are not really recognizable as progressive in most of the US or world. It's more of a factional battle in the culture war than about what are more generally agreed to be progressive values.