Even bundlers can be pretty stupid and simple. I still just use r.js for even large apps. Webpack isn't hard to set up, either. But my frontend code has almost no dependencies... I refuse to deal with React, Angular, etc etc. I have a very nice, simple component-building / screen scaffolding system that's about 1000 LOC. You extend the component and load up some HTML and just work with it directly in JS when you want to update data, resize it, etc. There's no need for all these frameworks that try to plant logic back into HTML. I love having the HTML templates pure and the logic unbound from them.