Imagine you purchased a multiplayer game on Steam and spent the last several months playing with friends, racked up a couple hundred hours maybe you spent money on a micro transaction because you don't want to grind. Now for some reason not specified if you want to continue playing said game you MUST create an account on the PlayStation Network.
But the problem is PSN is not in every country Steam is available in so Sony has effectively bricked a game you paid for.
In addition Sony has a horrific track record of protecting Customer, Employee, and Intellectual Property information. So some people are refusing to create an account because Sony is bad at security.