Comment by Rygian

I don't know. I guess they simply don't.

My approach would be to categorize user content into

- CRDT-enabled content considered as the norm, and

- content trapped in legacy containers that do not support CRDT.

With an implied warning for the user: legacy content offers a limited user experience.

Migration from "legacy" to "normal" should be fully supported, and as transparent as possible (but needs dedicated support for each file format). Converting "normal" (CRDT-enabled) content into files/blobs should be treated as a "take an snapshot" export operation.