Yep years ago I worked on a web application that was made with "classic" Active Server Pages. Each page was a self-contained .asp file. To make a new page, you copied another page and changed it around.
This meant that when you wanted to change something on all pages, it was a PITA but not always terrible because tools like grep, sed and awk exist for Windows also.
The nice thing was, you could make a change on any page and know that it would only affect that page and had no (or very little) chance to introduce bugs anywhere else in the system.
I wouldn't recommend the approach, but it wasn't all bad.
This meant that when you wanted to change something on all pages, it was a PITA but not always terrible because tools like grep, sed and awk exist for Windows also.
The nice thing was, you could make a change on any page and know that it would only affect that page and had no (or very little) chance to introduce bugs anywhere else in the system.
I wouldn't recommend the approach, but it wasn't all bad.