There is no denying that the information sent from client to server takes time, that's fact. Do you know what controls the speed of that packet? That'd be your internet connection. I'm glad you think I'm an uneducated random player but I've got enough certifications and years in IT to tell you that you're wrong. The post you keep linking is correct. It's the way the game handles input. Once the server receives your command to move it moves, not before. If your connection isn't fast enough/close enough/being bottlenecked somewhere that's why you're seeing yourself get hit when you're outside the red ring.

It's impossible to send data from one point to another instantly, hence the .3mms. The problem is magnified when your connection can't get the info to the server that fast.