ASP.NET Core can easily route "/hello" to HelloController.Index(), but it's not ...

ASP.NET Core can easily route "/hello" to HelloController.Index(), but it's not exactly automatic. The controller library adds routes to the routing middleware in a call to MapControllerRoute the app developer must make during startup which specifies a pattern.

    app.MapControllerRoute(
        name: "default",
        pattern: "{controller=Home}/{action=Index}/{id?}");

https://learn.microsoft.com/en-us/aspnet/core/mvc/controller...

If you don't call one of the MapController methods, requests will not be routed to controllers even if they exist in the same project.