> if your actions (or messages) are a liability, then why make them in the first place?
They may not be to begin with. Think changing morals or changing governments. Also I really hate this sentiment in general. Your solution is to just censor yourself. We're talking about about the abstract here.
> If you deleted your messages, it doesn't delete the record (from someone else's phone, for example, like a screenshot).
I feel like I literally addressed this above in my second paragraph. It's much harder to search multiple phones than a single phone that has all the information consolidated. Security is not about being bulletproof but that your are sufficiently difficult to attack. This distributed version of your data is harder to attack. That's the advantage.
> If the adversary is powerful enough (like a state actor), it matters not what your phone history is, because they can pin something on you anyway.
1) better something made up than something real. One is harder to fight and requires more resources for them.
2) what's the point of this comment? Are we just supposed to give up? No fighting back? This statement is always going to be true but isn't a meaningful trump card.