> Many configuration files in the Unix world were simply flat file tables, with colons, whitespace, or TAB as the field separator.

The main reason this was done was for shell scripting. Bash and Bourne, unlike newer shells like powershell, don't have any notion of structured input/output. It's string all the way down. So these simple table-like files with field separators were a way to put structure into those strings. It works out nice, because they play really well with awk.

But, such formats are a bit awkward now. You have to remember which program uses which field separators.