TL;DR, Phil Spencer responded to Digital Foundry's overview of the Series X by noting how Microsoft had to think out of the box, given Moore's Law is slowing down. Randy Pitchford took issue to that, and questioned whether or not Moore's Law is slowing down (it is), also saying that it just sounds like Spencer is making excuses for the Series X's shortcomings.
Equally interesting here is Pitchford's attitude towards the Series X - does he not have a dev kit for the platform, or does he, but finds himself not as interested by it (Gearbox's Godfall is PS5 and PC exclusive).