While I somewhat admire Timo's optimistic view of how data is handled in the cloud by companies who are known to profit from analysing, profiling and allegedly anonymising data for study and sale, the point I would like to reiterate is that non of the optimism or conspiracy matters when considering core of this issue that demands this feature.
All that matters is that I have have full control over the data I enter to this journal via established, peer reviewed and widely adopted encryption options that give me full control over my personal information. This is the only thing that determines the value of the features. My control of the data.
At this point in time we live in a world where it is simply naïve, at best, to think that companies like Google, Apple and Microsoft do not have relationships with intelligence and government agencies that they are not legally allowed to disclose. Handing over your data to warrants that you are not allowed to be informed about. Legal mass surveillance on a scale never known. A world where journalists are under the most threat of danger in declining democratic nations for having the wrong opinion of governments and companies.
There is simply no room for debate on this issue of whether the right to privacy is a fair or valid argument and a simple question would answer the necessity for this feature regardless of what you may or may not think about how much these companies care about your data.
Is the end user in full control of the incredibly sensitive and personal data they are entering or are there clear pathways to access that information should the user's database be acquired/accessed?
It's fundamentally that simple. It's irrelevant what, who or when an entity might become the bad actor. All that matters is that they can be compelled to do so and it could harm the end user because of the lack a solid E2E encryption solution.
We should really stop talking like "they don't care about your data" because we care and that's the only point that matters.
You could also let us sync to this https://cryptomator.org as being able to sync via cryptomator would at least allow the option to control data on normal cloud services.