What about basic business functionality, for example, a function to create a site URL, which can be quite complex, and which would be very time consuming and co

What about basic business functionality, for example, a function to create a site URL, which can be quite complex, and which would be very time consuming and complex and a maintenance nightmare if implemented in multiple languages. You could, of course, create this as a service. And then make possibly hundreds of calls to this service to generate a single web page. Or, you can provide a library that does this, and the calls are cheap, reliable, and predictable. Of course, if it is a service, the caller would locally the cache the information needed to make all the calls, do a batch call to the service, and then backfill in all the links. This then precludes generating and sending the page as you go, and creates the possibility for an explosion in complexity if a simple change in requirements that causes the arguments for the URL generation to be dependent on another service/library call. Not everything should be a service call.