[nonamegdsa]

I still don't understand what point you are trying to make. Surely you must agree that the number of requests per second your server will depends on what the server is doing? If your operation calls a DB or calculates something and that is heavy, then your db or internal calculation service might run out of resources. I'm not sorry, but your lack of experience with large scale systems is visible.

[SomeCallMeTim]

Most web sites are just grabbing data from databases. If you use an async front-end, it's the database servers that need to scale, because they're doing the heavy lifting. But scaling your database infrastructure can be orthogonal to scaling the application layer; in Node, except for under extreme load, you may never NEED to scale the application layer. And for really high load situations, you may need 25-50x fewer Node servers than PHP.

It's the poor design of most systems that cause them to not scale; there are certainly exceptions where the server needs to do a lot of complex calculations, but those calculations can most of the time be handled in microservices and, again, scaled orthogonally to the application layer.