If somebody finds it easier to do this process using Excel than with a scripting language, I wouldn't expect them to know the differences between file formats.

If somebody finds it easier to do this process using Excel than with a scripting language, I wouldn't expect them to know the differences between file formats. I would be surprised if they understood the concepts behind file formats. They may have chosen XLS because they used Excel back when that was default, and now they don't want to "risk" anything by switching horses mid-stream.