Mostly for myself this one:

UPDATE and DELETE considered harmful for OLTP. Everything can be captured with INSERTion of deltas. (Ref: Journaling).

Timelines. Very useful.

Revisionism is bad. See note about UPDATE and DELETE.

Interesting parallel with source code control systems.

To recapitulate: Everything can be captured as a delta and a reason, including correction of errors. Don’t use UPDATE.