I never heard of anybody saying "I'll use XML files instead of text files"

Except perhaps the root node of this thread, which said:

... a journal program with each entry stored in a txt file with the date as the file's name ...

I also have no axe to grind either for or against XML. I was merely picking up on the fact that the original question was specifically asking about XML versus plain text and I assumed your reply was too. Sorry for any confusion.