Guess you were so busy writing this very long piece that you failed to notice that in the current beta release Nabu Casa addressed ALL feedback that was given on the MVP backup feature, invalidating your whole ‘best’ example? And posted about this, pre release, right here on this forum? It shows you can chime in here just fine. Also with the month of WTH right here, of which several requests got implemented right away.
I would also like to note that without Nabu Casa trying to create value in their offerings, they would wither and not be able to build you anything at all. So as long as they keep proving that they never do so without allowing others to do the same (or users to do it themselves) they are welcome to do so.
To use your own example: Local Samba storage and other cloud providers are included as backup options, so you are in no way forced to support Nabu Casa in their contribution. Encryption is common sense when you store personal data and especially all kinds of credentials online, but you can turn it off for local if you want to.