people use php nuke because its easier, and they have yet to learn a programming language using a database or flat file, (such as php-mysql, or php-txt)...They may enevtually learn this through manipulating nuke, then once they find out its pretty easy they move on to make there own
, personally though nuke kinda sucks, its a bit hard to customize and waste of tiem when you can make a easier system on your own...