If it were $3675/business/year, I might agree. But $3675/server-instance/year is insanely expensive for many very real businesses. That's $300/month! Imagine a business like Shopify, but with one server instance per customer. No way can you afford to do that if you have to buy nginx pro for each instance. Unit economics still matter to lots of businesses.
That said, you can run quite a big site without any of these features just fine. Also nginx is open source and you can implement these features yourself, either using C or Lua, relatively easily as well.
nginx is a reverse proxy. You're not meant to be running dozens of instances, you're supposed to stick one instance in front of a whole collection of application instances. Your nginx costs don't scale with your server load, they scale with your infrastructure complexity.
That said, you can run quite a big site without any of these features just fine. Also nginx is open source and you can implement these features yourself, either using C or Lua, relatively easily as well.