It's not a necessity that the machine must slow down with each OS update. Boot an XFCE on Linux image to establish a baseline level of performance. Make that your OS and you can _buy_ from guys selling 2012 computers.
No one said that it was a necessity. The fact is that Apple software needs more performance over time so they shouldn't skimp on the hardware, or sell "old" hardware.
Why are you introducing an irrelevant tangent into the conversation? I have an old Dell in my closest that has Linux on it. But once again, that's irrelevant to this conversation.
