Linus' beard maybe isn't yet long enough to count as "grey" but, in any case, he's not a millenial. He entered the field circa 1990, whereas this self-proclaimed greybeard author started in 1995.
So for the discussion of this article Linus is even older/greyer than the self-proclaimed "get off my lawn" author.
Zuck is a millenial but he's far more of a businessman than he is a programmer.
Zuck hasn't really programmed since Facebook took off. He's a business owner/operator, not an engineer. Writing an MVP LAMP webapp that is then fixed up by others is NOT the same as having an influence on the processes and procedures used in the construction of software--which is what the OP is complaining about.
Facebook was a business success not a technology success.
Facebook was anything but a Myspace rip-off, Myspace was to Facebook as Geocities was to Digital Ocean or Altavista to Google.