their given reasons are "to keep backups" and "academic and clinical research with de-identified datasets"
they seem to actually do a fairly good job with anonymizing the research datasets, unlike most "anonymized research data", though for the raw data stored on their servers, they do not seem to use encryption properly and their security model is "the cloud hoster wouldn't spy on the data right?" (hint: their data is stored on american servers, so the american authorities can just subpoena Amazon Web Services directly, bypassing all their "privacy guarantees". (the replacement for the EU-US Privacy Shield seems to be on very uncertain legal grounds, and that was before the election))
no it's not. If you reduce the information in the datapoints until none of them are unique, then it is very obviously impossible to uniquely identify someone from them. And when you have millions of users the data can definitely still be kept interesting
(though there's pretty big pitfalls here, as their report seems to leave open the possibility of not doing it correctly)
dude, phones have built-in functions to transfer data seamlessly, i helped my dad with that a while back and it amounts to pressing some buttons and putting the phones on top of each other..
if that's too difficult i think you need a personal assistant.
Phones get lost, stolen, damaged beyond repair. I knew a woman whose phone fell into a body of water on vacation and couldn't be recovered.
When you have an app used by millions of people, which they depend on for tracking wellness, health issues, reproductive planning, etc. it makes sense to have a cloud backup for those inevitable situations.
Also yes, not everyone knows how to initiate an NFC file transfer, or even how to navigate their phone's file system to select the data to transfer. You often have to develop software to the lowest common denominator. There's open source options like Mensinator for people who want more control and privacy, but most software on the app store is targeted at less technical people.