Thats not a silly question, but I think in the context you're talking about (multiple users/clients working on a shared server install of SoapUI) its not how it currently works - it is something I wondered about trying to code though e.g. making a web ui ...
SoapUI, in terms of project creation, is designed to be a local desktop application.
Once a project is created, it can be excuted remotely using scripts possibly across multiple servers e.g. in the context of continuous integration.
Also muliple users (with seperate local installs of SoapUI) sometimes collaborate on a shared server based project (often stored under source control), composite projects can help avoid contention here.
As you are here, I believe that you might know about the SoapUI software and hopefully you started using it.
This tool is used to test our applications which are using based on API's like soap, rest, jdbc.
You can create project and use it when ever you need to test the application. The SoapUI software is installed on our desktop, laptop etc.
Another use case is that some one wanted to run the automated tests which may lasts for couple of hours and don't want to run it on some machine which is in data centre or in a lab instead of running from our desktop etc. I believe you were referring to this in your question. This is helpful for organization to achieve continuous integration for their mission critical applications. Again like to clarify that there isn't any thing called server for SopaUI.