Everytime this topic comes up, I can't help but feel the real divide on metagaming comes from one key concept:
Should the game challenge the player vs. Should the game challenge the character.
Players that want the game to challenge players usually don't sweat metagaming and IC Vs. OOC knowledge. To them, they're looking for a fun time being challenged and overcoming trials through clever thinking, tactics, and decision making. They would rather legitimately not know how to solve a problem, than pretend they don't. They're looking for real challenges, not pretend ones. It isn't about deciding what their character does or does not know, because the only time that matters is when they're challenged, and they can usually come up with any number of explanations for why their character knows trolls are weak to fire.
My observations show that generally it's the older gamers, the ones playing for many many years that prefer to be challenged as a player.
Players that want the game to challenge them as a character are looking to play in an interesting story. It isn't always whether the combat or trap or situation is difficult to solve, because they may already know the answer. It's about how the situation affects this character. What makes it different from other characters. Separating character and player knowledge is important, because the story is important, and consistency and immersion are the key to that.
In my observations, it seems it's usually the newer generation of gamers, or at least ones that haven't been playing for decades that gravitate to this style.
To me, it seems that these arguments rise up because the two sides are almost anathema to each other. Players looking to be challenged hate false challenges and playing pretend. They just want to play the game. They view such efforts as pointless or wastes of valuable play time. Players looking for their character to be challenged view metagaming as the next best thing to cheating. To them, it's ruining the consistency of the story and the potential to see how the situations reflects with the character they're playing. Convincing the two sides to play at the same table is like mixing gasoline and fire.
The best I usually hope for is just that either side can respect that the other prefers a different kind of challenge and wish them good gaming.