Tried some short gmail handles, can confirm. Creepy and stupid. Cloud-based datastores coming with your browser (aka what Chrome has* and probably its competitors too) have better performance, privacy, and UX; I can't think of any reason why I'd use something like this.

* - AFAIU if you set a sync passphrase you also get some (probably limited) form of "zero knowledge" client-side encryption; this makes me hopeful they implemented it properly i.e. "we literally can't access your shit" https://support.google.com/chrome/answer/1181035?hl=en

ok, how does that work: did all those people sign up with Magic?