@mietze My suggestion? Instead of focusing on how to limit your playerbase, focus on how to empower them. Allow your PCs to run PRPs with no (or extremely few) hoops to jump through. Employ players to assist with jobs that you don't want to do (build jobs, apps, etc) so that you can focus on STing if that's what you want to do.
Yes, a game with a lot of characters can feel overwhelming at times, and maybe you can't touch EVERY SINGLE PERSON EVER at all times, but you should still be able to involve active players if they want to be involved.
If you want to focus on touching every player individually, then limit your playerbase from the beginning with the acknowledgement that you're going to be consistently opening the gates to let fresh blood in and have to repeatedly figure out how to catch the new people up from a game that was closed/blocked off for periods of time. Which tbh sounds freaking exhausting.