I last used Dropbox in 2011 or so (I stopped using it because it killed my battery life). It may have gotten better since then. (But my point is addressed to what it takes to get popular, i.e. that its easier to make a “dumb” tool popular, and Dropbox was popular back then.)
Going out on a limb here, but I think it's possible things have changed in 7 years (and that it was probably something specific to your setup, not something millions of Dropbox users with a Mac had to put up with).
> i.e. that its easier to make a “dumb” tool popular,
If this was your intent, then using the tired "worse is better" trope and claiming an issue from 7 years ago, that no one else has claimed to have seen is seems a far cry from it.
Dropbox became popular because it was easy, it worked, and did exactly what it said it did. That might be "dumb" in that it's not feature packed, but you use a lot of negative connotations when none are required.
EDIT: Clearly not just me: https://news.ycombinator.com/item?id=12464901 (thread from 2016)