WoW for sure had this kind of thing too. I remember because I played from vanilla to MoP. High population servers would be marked as full. (I remember Blackrock and Proudmore being pretty much locked for a good while, I was on Eldre'Thalas which got close to full for a while) I think it's not an issue anymore because there's a lot less people playing WoW than back in BC/WoTLK. In your specific instance you could make a character on any server on Dynamis besides Seraph. It doesn't matter where you make a character because you can freely visit any NA server on any data center at any time, so just pick whatever is open.