Nitpicking: The 5060 is high end? Back in the day, we used to call *60s "midrange."
People keep assuming growth to be infinitely linear, despite every historical, real life example proving that this is impossible.
Node shrinks are one thing, but avenues for improving the logic itself are not infinite either. Lack of competition most likely has an impact, but even with it, it's not guaranteed we would get to the good ol' days. At the very least, not without some revolutionary breakthrough in electronics, software/math, or both.
Accusations are easy, proving them rarely is.