It takes some of us back to when we were kids. From the moment we could count, some of us liked ranking things, whether it was toy cars or stuffed animals. It wasn't something you could measure, necessarily. You could come up with whatever criteria you chose, you could build rational arguments and, generally, there were no wrong answers.
Ranking footballers, to some degree, is a similar exercise. Or, rather, there are wrong answers -- pick Jesse Lingard over Lionel Messi, and someone will remind you that you're entitled to your own opinions but not to your own facts -- but there aren't necessarily right ones.