When did file sync become easy? I agree it's become commonplace with Google Drive and iCloud bringing respectable implementations to market, but I think it's still far from easy.
It's easy from a consumer point of view in the sense that it's readily available and easy to set up. The fact that it is still technically difficult to set up from scratch doesn't matter to consumers (or businesses) when there are multiple providers that hide that complexity for the end user. Hence Dropbox no longer has a competitive advantage from having produced a solid solution to a difficult problem.
Right, except the stories of data loss are an order of magnitude more common with Google Drive and iCloud compared to Dropbox, so even though at the surface level it may be a classic market for lemons, I still think Dropbox has a competitive advantage based on their reputation.