I'm unclear about what the real-world examples behind "Disengage" action, thus this question.
What's the difference between readied attack when an enemy moves away from you, and an Opportunity Attack? Both use Reaction, so arguably it's not "because you are ready, and Opportunity Attack is impulsive".
By the intent, what's making this type of ready attack unavoidable (or avoidable) by "Disengage" action?
I'm just looking for the difference between the two attacks, and the rationale of allowing/not allowing Disengage action to avoid Opportunity Attack but not Readied Attack.
By rules, I know Disengage specifically only avoid Opportunity Attack. So an ideal answer should cover what real world example of what constitutes as "Disengaging" that allow one to prevent Oppportunity Attack but not Readied Attack. A designer's intent is nice to have to provide insight on the rationale.