Those cities are much larger, both in size and population. DFW is 8x the population of SF. According to Google, at least.
Meanwhile those new building numbers are NOT 8x.
Meanwhile those new building numbers are NOT 8x.
As of 1990 (the point where the graphs diverged), DFW had 3.8M people, Greater Houston had 3.3M, and SF/Oakland had 3.7M. They were pretty comparable then; subsequent growth has been simply because the Texas metro areas have added more housing.