luenskifreeman, The PC and Mac are just computers. They have basically the same hardware. Macs also have an application to run the Windows operating system, so that may be the reason it can be transferred via computers. When the game originally launched in 2014, it was PC only. It became a digital only purchase for Mac in 2015, so it took a few months to make it happen on both. The reason they are interchangeable is most likely because Mac have the application to read things usually made for Windows operating system.
EA had to create a seperate team to convert a 3 year old (at that time) game to work on consoles. It isn't as simple as you believe. The game had to be basically remade using different developer tools from Xbox and Playstation respectively and realeased in 2017. Each console has a different operating system, which do not communicate with one another. That is the best explanation I can give without being too technical. It is why you can transfer between similar console platforms but not to different platforms. This also explains why the computer platform can get patches faster, as the approval process isn't needed. Right now, they do have to run it through for approval with each console platform.