The problem is that with each platform they introduce, it takes more time to develop and test each patch. Lead Engineer Bill Warnecke answers a similar question about the Linux platform:
Hey there! While many of us on the development team love Linux we are not currently looking at adding native support.
Dealing with the code changes required to support another platform is one challenge. Outside of the Overwatch code itself we would have to work with internal and external teams to update libraries we depend on. Tools like the [Battle.net ](http://Battle.net) desktop client would also require changes.
On top of all of the above we’d have to split our QA time to make sure we put the same level of quality and polish into the Linux version as we do for PC, PlayStation 4 and Xbox one… and this has to happen for every patch we put out.
We learned with death match to never say never, but for right now native Linux support isn’t a focus for the team.
Cheers!