TACO is not the same as admitting a mistake.

Admitting a mistake involves some amount of learning not to make the same mistake again.

The reason this is important practically speaking can be seen in situations like chaotic tariffs and threatening allies.

The TACO move might allow us to step back from the cliff in these situations but the fact that we keep being on the cliff on a weekly basis means every other world actor has no choice but to make plans to have us committed in the long term, and this is going to cause huge, long term problems for the US economy.

Aesop's fox and "sour" grapes.

He chickens out, but can't admit to himself that this is what happened.

It got replaced with a simpler system of comparing attack rolls to the AC directly.

Oh, wait, that was THAC0...