YIMBYs believe that increasing the supply of “housing” will lower “prices”

YIMBYs think building higher is a “technology” that is “banned” deploying which will “lower housing costs”

The basic idea of supply and demand is that producers are willing to supply more of a product at a higher price point, and vice versa for consumers. YIMBYs are thinking about a shift in the supply curve which usually occurs when there is a technology change that lowers costs