Dropbox can be swapped out with other storage services.
At least on iOS, this doesn't appear to be meaningfully true. With 1Password if I have navigated to a site's login page in Safari, all I need to do is hit the 1Password Activity button and it will populate my name and password.
With "Keepass Touch for iOS" my options are either: "You're browsing wrong. If you want to log in to something, use the integrated browser" or "switch apps from safari to Keepass, copy username to clipboard, switch back to Safari, paste username, switch back to Keepass, copy password, switch back to Safari, paste."
No thanks. This is still meaningfully behind in the usability department.
And ultimately, the point is 1password’s db should be well encrypted so you don’t have to trust the underlying storage.
Not so much. My creds were leaked in their 2012 breach.
https://techcrunch.com/2011/06/20/dropbox-security-bug-made-...
https://www.theguardian.com/technology/2016/aug/31/dropbox-h...
The passwords should be encrypted at rest (and are with KeePassXC), so Dropbox' (or iCloud's, for that matter) security is irrelevant.
Disclaimer: Using 1Password 5, which was a one time payment.