"I don’t think a reasonable evidence-backed case can be made for your implication that Mac laptops are designed to be obsolete more quickly than, e.g., HP, Dell, or Toshiba laptops."

Just more obsolete than all the laptops that can be serviced and upgraded without the same restrictions. I wouldn't go lumping all of the models from all of those makers and settling for a blanket statement like that because that reads false just by picking one model that passes the conditionals, just one per any given maker.

In the end it is a choice and some will try to sugar coat that choice with whatever makes them feel better about it.

But if you have to imagine a given brand tops the lot because you "don't think a reasonable evidence-backed case can be made", when it clearly can, that speaks lots about brand engadgement from your part as a customer and not much else to the merit of that brand, and stand for the ethics behind it.