I personally just make up rules and don't really consult with the players about the changes, merely inform them. I often have to modify them in the middle of a campaign because quite often it turns out that the initial idea conceived in a vacuum is... Bad. Who would've thought.
And I can certainly see introducing a new rule that would make taking prisoners easier, letting players figure it out, adapt to the changes in the metagame ("metagame" as in "general reasoning of what constitutes a bad/good position, expected enemy strategies, wincons, etc" — like, general gaming sense, not weird TTRPG jargon) and then putting the new mechanic to the full use as a perfectly viable technique.