I worked for a few years at an agency that adhered very closely to these principles, and you know what? When things started to rapidly change around 2013 everyone was consumed and overwhelmed, and when it came time to necessarily onboard them on new technologies such as build systems, css preprocessors and the like, the skepticism was so profound, and caused such a problem for those of us looking to make everyones li…
I watched a company almost go under(shrank to almost no employees) after exactly what you described. The BFEDs(including the CTO) refused to update their skills and the company tools/stack and the company was beaten out by competitors.
If you decide not to use a technology because the developers can't or are unwilling to learn them, you've got bigger problems than technology choices.