On the contrary, I completely disagree even if it is against the common opinion. You do not need to be part of the elite 1% to care for maximisng your performance.
Logic dictates that you will prepare your character based on hard evidence may that be numbers or ingame experience. This means that you must be completely ready before start worrying about raid setup or tactics.
At the end, all you have to do is to put the right talents/encahnts/gems/reforges. If you fail on that, you have no right whatsoever to criticise anyone or anything ever.
If you value the 'feeling' of a certain mechanism that makes it more enjoyable to you, more than the 'correct' but boring or irritating choice then you are not supposed to be raiding.
Any leader of a guild that has ambitions to make proper progress which does not necessarily mean be in the top 1 or even 10%, will start his raid by picking people that know what they are doing. The rest have no place in a raid. Wow is min/maxing. Period! Especially when said leader knows that his material isnt the best he could have and skill cannot compensate. Everything else that can be easily managed such as talent choices has to be of 100% efficiency.
Why would you force anyone to raid with you and actually carry you, even if you have the raid dps for a fight. Now, if you ( in general) are a guy that just wants to 'have fun' at the cost of performance in a casual guild, then think again cause no matter how you see it, you are wasting your time.
The DK example is out of place. That talent choise actually comes with skill required and it can hurt more if you mess up although maths prove otherwise.
In any case even if 1% isnt the end of the world, it should matter to anyone who does not want to intentially deprive themselves of the absolute best the can deliver.
This is not elitism, it is common sense.
TLDR: You dont need to be hardcore to choose performance over fun. Actually every average raider should value performance more. If not, they just lower the fps of those with the standar intelligence quotient.