I wrote my first web app with Django. And then Rails. These frameworks taught me how a web app should be structured (models, views, controllers, services, migrations, middleware).

Now, if I wanted to, I could build my own application without Django or Rails, as long as I had something to accept incoming HTTP requests, make responses, and a library to make DB calls.

But I wouldn't have gotten to this point had I not learned Django and Rails first.

I think using a framework turns many "unknown unknowns" into "known unknowns".

I can read my framework's documentation and learn it has built in logging, so logging is something I need to think about when building a web app. It lets you filter sensitive data from logs, so that's something I need to think about.

This is why I was building a type of application I didn't build before, I would look for a framework I could use, or something like it.

I'd use go kit for building a microservice for example. I don't get many of the concepts involved with building a microservice (circuit breakers, service discovery, etc) and hopefully the framework would help me learn them.