I don't think anyone commenting along these lines on HN is that ignorant. Everyone on here understands that anything executed at the WhatsApp/FB/Instagram sort of scale is going to present all sorts of tough problems and require software engineering know-how in spades.
However of all the various applications you could conceivably scale to hundreds of millions of users this is one of the simplest. I do not think acknowledging that is cringeworthy at all.