What makes macOS 11 Big Sur supported on a 2013 MacPro and not a 2012?

Solution 1:

As to the reason why Apple chose this exact model as the cut-off point for support cannot be answered by anyone but Apple. Everything else is just speculation.

There exists an non-official guide on how to install the Big Sur beta on the older 2010/2012 Mac Pro's (amongst others):

https://parrotgeek.com/bigsur/

Note that because this is non-official, it might not work or exhibit problems. Also it might only work for the current beta, and not when you get to the final release of Big Sur.

As indicated in this guide, the built-in WiFi does not and there could be issues related to sleep mode. This could hint at why Apple does not support this model - i.e. having to support these older WiFi chipsets.

Solution 2:

On a technical level, the installer has to have all the drivers needed to make the hardware boot, so the installer will check and abort if the model is not on the white list of eligible gear. Also, Apple may have run the code on the drivers and found they lacking entirely and had an estimate to support it that didn’t match expectations.

On a program management level, Apple has to spend time testing each release against a fleet of hardware so they can test everything. That money and time is surely reviewed to determine the costs to support older hardware.

Finally, on an experience level, Apple has to measure how the software performs and decide if they can even support the new code running on hardware that may not execute code as fast for whatever reason (drivers, latency, CPU features) and might decide the experience isn’t going to be good or they would rather invest money and time elsewhere.

In the end, only Apple can know what and why the decided this, but I’m sure people will figure ways to hack gear that’s not officially supported, but the official support moniker means a lot for some so it’s worth checking your requirements before you upgrade.