I'm willing to be the dumbest member of this community. But on the off chance anyone else doesn't understand what problem Nginx Proxy Manager solves:
Many ISPs only allow traffic on ports 80 and 443. But distinct from a website where all pages are part of a single process, separate web apps (photos, blogs, calendar, etc) are all made by different people and need their own port.
Nginx Proxy Manager can therefore be the only thing listening at ports 80/443 and then can seamlessly forward the user to the correct port using HTTPS.
Smart people: constructive critiques are welcomed.