It's about being objectively rational vs subjectively rational opponents. For example, look at how gtorangebuilder calculates the best strategies: by putting starting ranges against each other and finding the comaxexploitive strategies. These are not necessarily Nash Equilibrium strategies because the starting ranges are not necessarily correct, but by calculating the best strategy given a set of starting ranges, gtorangebuilder finds strong strategies. Of course, these strategies are non maximally exploitive vs non optimal opponents, but they're quite strong nevertheless.
Necessity is the mother of invention.

Regret Aversion and showing cards.

Over in the Poker Tells/Behavior subforum, an interesting thread about “show if I fold” speech play happened.

“Will you show if I fold?” is apparently a common attempt among speech players to get a tell from opponents when deciding to fold (or call, or raise).

One player asks the other “Will you show [your cards] if I fold?” and waits for a reaction. The thread was discussing a best response to this among speech players that are expected to respond to such questions (not answering is valid but may be misinterpreted as a tell by an otherwise talkative player).

The thread was delighted when one thoughtful response was:

“ I may not show if you call! “

Poker players are entertaining even when they are trying to take rent money from one another.

But what is the basis for such a question? Why would humans ask each other such a question? Even just to elicit a tell, what is the shared commonality between these humans that makes such a statement even understandable?

From an econ standpoint, such a question is pure gibberish.
Yet, the question makes sense to humans.

This is because humans experience regret.

Simply put, regret is when humans make a decision and are informed afterwards that they were incorrect.

Regret Theory is the theory that humans anticipate regret and factor this anticipation into their decisions. When regret anticipation leads to irrational decisions, such as holding onto a bad stock or a bad hand of poker, this is regret aversion bias.

Poker players who participate in speech play are often deceiving each other, with the understanding that such deception is implied and understood by sophisticated opponents, and a reliable source of tells from naive opponents.

So lets see what is being said in the “will you show” conversation:

Player A says: “Will you show if I fold?”

Literal translation: I am considering a fold, will you inform me after such a decision if I was correct?

Analysis: This relies on the listener to know the concept of regret. Humans do not enjoy regret. Humans avoid regret. Human poker players do not enjoy and try to avoid regret. So why would a player ask for regret?

Maybe just for confusion, or out of genuine curiosity about a particular opponent’s strategy in a certain situation. Both of these are valid. But there is more to this conversation.

What is the tell that the speech players are fishing for?

It is in the eyes and face of player B. It is regret, or the relief of same. It is either the anticipation of receiving pain or the joy of dishing it out.

Player A is REALLY saying, “will this hurt?”

The challenge for player B is to know the answer, and resist the opportunity to “tell” the secret.