yes, selection bias but the fact that he had a constant stream of people thinking that proves the point that many folks just don't have a freaking clue about how computers work or what's responsible for what.
No one is disputing that there are many people like that; the question is, how many in relation to more savvy customers, and whether this amount is in any way significant for the company.
To build on and adjust that: you actually want to compare how vocal the people like that are.
Since tech-savvy folks tend not to contact support, I'd wager this would've been viewed as significant.