It is because it is too obvious, if you want to name a file something that you don't want others to know about, go for something a little less predictable. For example, your friend gives you a file that has loads of games that they made or legally downloaded, but they don't want anyone else to know that they have said games because they are specifically for you. They aren't just going to name it "Games that I got for (Insert name here)" they would name it something both themselves and you could understand, but others could not. Now, that is if you want the contents to remain anonymous. If you want it to be obvious, then the name like that is perfect. If it isn't supposed to be "encrypted" in a way, don't.
