Come on, calling the comment a conspiracy theory is hyperbolic.
(As I am typing this, I'm three letters ahead of the text appearing on the screen).
There are always improvements in the development of new products, everyone expects that, no conspiracy is implied. It is simply that it is very dissappointing and inconveniant if the product begins to perform poorly.
The question here is, does it have to?
Your old Ford's performance will diminish with age, but if you fully restore it, it will perform to original specs.
My old iPad is not worn out, the microprocessor, memory, display, etc, are all in good working order. The iPad as a whole however does not perform at the same level as when I bought it - because of the inabailability of an OS that allows it.
So, that Model T required leaded fuel, but you can restore it and put an additive in the gasoline to let it run like new.
As the OS's leapfrog the apps, and the apps catch up, the older iPads become less capable of original performance, is there a fix? Does Apple have the incentive to keep customers of older products happy? Probably not!