The final part is:

Beancounter executives then cut a key piece of hardware spec (ie, memory bandwidth or capacity) to save 5% unit cost. Product then fails to meet sales expectations and concedes defeat to competition in following cycle.

sigh

Welcome to modern outsourcing. "Brand" sends out 'request for bid' with a list of 'requirements'. OEM's work on what can/can't be done with existing/future hardware that may or not meet the needs/requirements.

Once the major technical details are worked out, the "Brand" may have further size/shape/packaging that they wish to add.

Not sure about the title there.  As someone working in an engineering environment I very much doubt that Microsoft operates much differently.  If the engineers at Microsoft aren't working with AMD I very much doubt that is a reflection of their competency or commitment.  There is always some product owner, all to often someone with no technical acumen, directing those engineers as to where their time is to be spent and what their priorities should be.  If Microsoft isn't working with AMD, it's because leadership at Microsoft has decided they don't want to or it isn't worth the time.  Nobody is slacking off or dropping the ball; this is, I assure you, a choice and one not made by the engineers.