That's less common wisdom and more of a catchy but dumb meme. There are all sorts of things you can buy that have crappy-to-nonexistent customer service.
As with every generalizations, there are exceptions, but they generally only prove the rule.
Customer service has more to do with company-specific culture than what you actually paid. There are good and bad examples in every industry (or even with the same company).
But that doesn't contradict the point of the comment you were replying to, does it?
Edit: You should reply instead of just downvoting.