The problemAtom is a very nice text editor for OS X, but it comes preinstalled with a package called Metrics. By default that package reports usage information to Google Analytics including a unique identifier that is generated by computing the SHA-1 hash of the machine's MAC address. I am sure there are people who don't like that. For example one could get the Mac's mac address by using rainbow tables.
Well, the information that is being reported to Google Analytics is well documented on the Atom's FAQ and github, but the instructions how to disable it are pretty spartanic IMHO: "If you do not want this information reported, disable this package from the Metrics section of the Settings view".