Another one is storing data, Apple for instance can easily lock in users with iCloud because it is so much more complicated keeping all devices and apps in sync

Another one is storing data, Apple for instance can easily lock in users with iCloud because it is so much more complicated keeping all devices and apps in sync without, with iCloud you have one login for passwords, browser, files, etc. In theory a shared folder with clients that handle multiple devices/operating systems in their dot-files well would be able to replace that, but with most phones in a closed ecosystem, I don't see that happening.