[laumars]

I wouldn't say obvious. The reason you and I would have engineered the kinds of solutions you described (albeit I'd use HTTP(S) rather than FTP(S) because FTP needs to die) is because we would have designed something that didn't require installing additional software on the client machine (I mean other than what you'd normally expect on said machines).

Dropbox was originally scorned on HN because they took a different approach yet history has now proven they had a good idea.

So I wouldn't say it was obvious at all.