Javascript for backend was a mistake. Setting up a whole project and tomcat and docker and blablabla is so much effort. There is no option that's just easy 100 lines in one file for something quick and dirty.

On the other hand, in frontend we just developed something as simple as html. You can write css right into it. You can even write a little javascript just into it. You can even open such an html file from your file system. You can ping backends with curl. You can ping websites with python/requests. Sure you can set up a big project with Angular/React, but you don't have to.

Why have frontend/backend developed so differently? Why is there nothing as slim in backend has html is in frontend? Or do you have something for a usecase like this?