Yes, everything about WhatsApp is so trivial that Facebook with their billions and billionaires and 1000's of high-quality engineers decided to spend 18 Billion dollars on it. But of course they're all dumbasses because you say it's all 'trivial', right?

I think it's pretty clear that Facebook didn't buy WhatsApp for the technology itself but rather the large market penetration/installed user base. Whether that was stupid or not is up for debate.