My opinion is simply... its a roulette. You don't get to pick and choose the strategy or your party members. People que in for different reasons and may not have patience to wait for someone to learn a fight. If you don't like it, you can attempt to kick them and if the kick fails then deal with it and que with pre-mades in future. You may not like them locking u out of the fight and finishing it solo but it seems like they dont want their time being wasted.
Not to sh1t on good or bad players. Im just saying that PUG's aren't an ideal way of completing content with specific goals. Pre-mades are better for that cause you gotta deal with what u get in duty finder.