Have you seen how many servers have been release since launch? They have been using the scaling aws offers to go horizontally by adding more servers. You can only scale vertically (allow more resources per server) so far. People who played the beta and saw them increase the caps know how buggy and laggy it was with high populations allowed.
Side note to maybe help: You can use a service such as New World Status (or in game world list during character selection) to check for a lower pop server. Yes I know its not “ideal” to “lose progress” but they are adding free transfers soon. I have went to a lower pop server and been enjoying the game and plan on transferring when i can to a server with all my friends. – Cheers!