You’re comparing lots of things here with very different reason of existing and even very little to do with each other imo.
Comparing wordpress to languages you can use to write fully custom sites is not exactly right. They both are valid depending on what you’re doing.
Npm nobody cares if you use npm or something else (like yarn). It’s a package manager for node. But you’re probably gonna use it if you use node as it’s the most popular.
If your product is a web app that “does things” you’re probably not gonna use worpress to make it. But rather some php, node or c# stack or whatever. You still might use wordpress for the companies website with contact info, product information and stuff. Wordpress makes arguably pretty sites fast. That’s what’s it made for.
NGINX I think a lot of the time now is used purely as a reverse proxy and load balancer. Many frameworks in node, or c# or whatever come with their own way of actually running the app, but you usually don’t expose that app as is to the internet. But rather have one nginx on port 80 and 443 and forward to the other servers/services. Those might run on say port 5000 internally or might exist multiple times in docker containers, in witch case NGINX could act as a load balancer.
As for webhost I’ve been using digitalocean for a while now. There you can make linux VMs, either custom or 1 click-apps (pre-built images) that may contain forum software like discrouse already preinstalled (this forum runs on discourse and discourse itself is free too) or LAMP stack or wordpress setup or whatever.