A Mythic+ 10 does not require mastery of the entire game. If one person makes a small mistake and your knee-jerk reaction is to abandon 3 others, 4 including the person who made the mistake, I'm sorry, but you're the douche.
In Legion, I was doing +25 with my Mythic guild. I know how frustrating it is to make mistakes or for others to make them, but that's not an excuse to be an asshole. But I guess anonymity protects people like you.
Please try reducing your hyperbole.