Developer productivity: how much better are modern (2018) web frameworks?

I've been using Django since I first learned to code a few years back and only have experience with that and Node.js thus far. I personally really enjoy working with Django.

I was wondering what HN's thoughts were on the magnitude of productivity gain from using these modern frameworks and paradigms, and how that productivity translates to the performance of a business.

Obviously, YMMV based on the company's industry, structure, experience, and other such factors - but, ceteris paribus, what are the opportunity costs of using ASP.NET or PHP (for example), if any?