I have to disagree. PG's essay was discussing immigration at a
very broad level, and as such so are the comments in this thread. You seem to be asserting some definition of "what PG said" that isn't apparent in the essay itself.
The crux of PG's essay was this (taking from what is a sort of his thesis statement):
> American technology companies want the government to make immigration easier because they say they can't find enough programmers in the US... The technology companies are right.
He mentions things like how difficult it is to train programmers, and uses the word "great" in describing said programmers, but overall everything is backing up the blanket statement that "we need to allow more programmers to immigrate" without providing a discussion as to how that should be done.
As such, what you call "genetic tangents" are directly addressing the main point of the essay. H1Bs are the main method through which immigration occurs currently, and one would be remiss to have a macro discussion about immigration without mentioning the H1Bs.
I assume that there has been some sort of discussion or knowledge about PG's stance on the tech immigration, and perhaps even related to this thread, but I would argue that the fault of the imprecise nature of the discussion of this essay lies primarily with the essay itself.