[dragonwriter]

> It is essential to a competitive game that everyone try their best in that specific instance of the game.

No, its not.

It is, of course, more desirable from the perspective of people who prefer that style of play that others conform to it, but it is in no way “essential”.

It may be beneficial to mutual enjoyment to have table agreement on metagame issues like this in advance (OTOH, one might do well to recognise the inherent incentive structure toward the metagame approach you decry in games which tend to produce a long, lingering defeat with no reasonable route to victory.)