Have you watched the presentation referenced in the article? CRDTs have come a long way. You can get down to about a 150% increase in size over a plain text representation. Since most rich text formats store the edit history anyway, this is closer to feasible than the numbers might suggest.
yjs[2] is one CRDT that handles text reasonably well, but it can still run into performance edge cases (as they plainly/honestly admit in their README).
[1]: https://github.com/automerge/automerge/issues/89 [2]: https://github.com/yjs/yjs