A lot of people fall into the trap of negativity = IQ. Your brain can spit out a reason that DropBox will succeed or fail, but the failure case sounds smarter.
It wasn't. Even the famous comment just pointed it was possible to replicate with existing tools. And apart from one person the thread was actually pretty welcoming.
That comment was just a grandfather of the very popular "Why should I use this instead of [completely different solution]?", that is also so very often also used against open source projects themselves.