The statement is not “web applications are complex”. The process of making something for the web is complex. Plenty of people far more experienced than I have complained about learning to build a web app and being told 50 things to learn. I can still add my experience though.
Before I did anything I looked to see if there were anything that could make python code just work on the web. Research found no project still bearing fruit.
In concept at least. I went into this project with some (limited) prior experience years ago. W3schools is still an ‘ok’ reference to get started. It doesn’t take much to get something displayed in the browser.