Has this been done before? If not, then why not? With all of the available services like this for Windows and Linux, why not Mac? Is there some sort of license

Has this been done before? If not, then why not? With all of the available services like this for Windows and Linux, why not Mac? Is there some sort of license fee or restriction that makes this type of service difficult to profit from? I'm just trying to figure out why I have not seen more of this type of service for Mac, especially with the large number of responses to this that seem to be really interested in it.