That still doesn’t overcome the issue that they are selling every single one they can already. They have no need for additional chip sales.
All the capacity at all the fabs is booked up for years. They can’t make more if they want to.
So any hypothetical sales of OEM style guts would only cut into the number of Macs they can sell to existing customers. And there’s no way they would ever do that.
Servers need a lot of RAM. Apple can either make 42 iPhones with 12GB or one server with 512GB RAM.
42 people with iPhone will buy airpods, some subscriptions and apps. They also be vendor locked into Apple ecosystem and almost guaranteed to bring more iPhone sale in 3 years.
Apple must be dumb to canibalize their own market.
They tried it with various open systems that allowed licensed powerpc clones of their systems and they ended it because it reduced their profits as people bought the clones instead of mac hardware. I don't see them redoing that anytime soon.