"Basically no non-Apple first-party apps support iCloud in any meaningful way. 1Password, Chrome, ... Plenty of third-party apps support Dropbox API.".
I can't wait for this to change (and I'm pretty confident it will). 1Password's Dropbox support really is terrible. My 1Password DB is not something I want to see, so I can hide it away in a folder in my Dropbox, but then a dot file is saved in my Dropbox root so 1Password can find it. The alternative would be for 1Password to force a hard coded path. Both are inelegant solutions to using a filesystem for app data syncing.
I can't wait for this to change (and I'm pretty confident it will). 1Password's Dropbox support really is terrible. My 1Password DB is not something I want to see, so I can hide it away in a folder in my Dropbox, but then a dot file is saved in my Dropbox root so 1Password can find it. The alternative would be for 1Password to force a hard coded path. Both are inelegant solutions to using a filesystem for app data syncing.