That's a very bold statement: "can't be built with that stack". A large portion of apps aren't built with Node or React, they're built with, say, Rails, Java/S

That's a very bold statement: "can't be built with that stack". A large portion of apps aren't built with Node or React, they're built with, say, Rails, Java/Spring or .NET backends and a front end framework like Angular. I get the theory behind React, the reality is that it is often a complete mess.