What one finds useful from a web application and what the web application actually is are usually two entirely different things.

I work in marketing automation, and I guess I have in one way or another my entire career. The clients who need to use the platform to communicate with their own clients over social networking may never touch our print delivery system, but that doesn't mean that print delivery doesn't exist or isn't important.

If you are unwilling to recreate the totality of the application in terms of functionality, then you are lying if you say that you have recreated it.