It's funny where this argument will pop up!
I have less of an opinion now than I used to on this subject.
The parts book that is a reference is dated in December. Everybody knows that the next year model is introduced the previous year. The c model would have been well and truly out by then. If it was dated in say, May,you would have a better case.
How many GENUINE arms are out there? How many will be modified c arms? Maybe it's not that big of a deal.
This thread is evidence of what is broken in Vintage MX.
I think you are looking at it too hard. If that is the case, lots of things are broken in vmx. It depends on your attitude towards it imo. There are lots of grey areas in vmx, but in general it works and works well. In most cases its the humans with their own agendas that try and stuff it up.