tbf I think the "I don't want to entrust all my notes to a startup that might not be here next year" issue is more relevant to the average person than "but surely you could roll your own if you were a desktop Linux user". On the other hand, I agree normal users don't want software to stick in docker containers, they want a nice friendly GUI that also happens to backup copies of their data somewhere they might be able to access them with another programme if the company ends their incredible journey.
One of the best things about Dropbox as an early adopter was knowning that if they died or got acquihired, you still had one or more local copies of everything you'd ever uploaded to them.
Oh, I agree that even Google isn't immune to "sunsetting" useful products. But I'd still rate files on my Google Drive as being a lot more likely to be still usable in 5 years time than a service from someone with a few million dollars in Series A funding to get big or die trying.
One of the best things about Dropbox as an early adopter was knowning that if they died or got acquihired, you still had one or more local copies of everything you'd ever uploaded to them.