Because for the vast majority of software, fast to build is far more important than provably correct. Because there aren’t any batteries-included RAD framework

Because for the vast majority of software, fast to build is far more important than provably correct. Because there aren’t any batteries-included RAD frameworks in functional languages yet. Because most undergrad degrees, if they touch on functional programming at all, do so in only a cursory manner. Because for most purposes a smart CTO will choose to develop a project in a language/framework that’s good enough and for which it’s relatively easy to hire skilled developers over a language/framework that offers some minor technical advantages but will make hiring even more excruciating than it is for widely-used tools.