Only because people are stupid, lazy & think the world & most else is static, then try to treat it as such... CO2 din't make you build on the ancient sea floor & in other stupid places & it didn't make you create synthetic chemicals that never existed & are toxic to you, it also didn't make you pave over the most fertile areas or build weak structures.

It didn't make you build the wrong thing in the wrong location for the wrong conditions... 

 And taking low tech off the table isn't going to help them.