Hi OP here, yes you are right, we have definately evolved the way we make apps over the years but fundamentally its just been a process of editing text, make sure its syntax is correct, make sure it compiles, run it, iterate.
I probably should have elaborated more on this in the post but I didnt want to make it drag on too much ;)
https://mikecann.co.uk/posts/tinkering-with-replit-agents
The conclusion is some parts were good and some bad!