You can keep it on other services, but economies of scale, bundle pricing, and security concerns benefit the large incumbents. For example, I stick to iCloud, because all of my data is already exposed to Apple, so exposing it to another entity is just increasing the number of entities my data resides at just increases my vulnerability.

However, as an individual, I could gain great utility by not exposing any of my data to any company. And I would not have to if I could setup a NAS at home with a 1Gbps+ upload that me and my family can setup our devices to backup to, or use in a similar fashion as Dropbox or run a peer to peer chat protocol like WhatsApp.

But all of that is a nonstarter because of the minuscule number of people with 1Gbps+ connections at home with ipv6 and not hidden behind CGNAT, there is no viable market for selling the software and NAS that can cut out the big tech companies.