> Isn't the view that people having extra homes they use 5% of the time a very well-known and common criticism?

Not by Sam Altman, surely. Hypocrisy is an individual sin, you don't get out of it because everyone else thinks you're wrong.

To murder the humor: the joke is funny because the idea that we should centrally plan resource usage for the benefit of society as a whole and discourage/disallow individually driven use of those resources for individually popular but socially wasteful applications is... communism, basically.

You can repeat this analysis for pickup trucks or cross-continent travel or desert agriculture, ad nauseum. And we do. And people like Sam Altman tend very strongly to be on one side of the argument. Until they need more DRAM, then it's all "let's pull together comrades".