If poor players only ever got matched with poor players for storyline stuff and then none of them were able to clear anything, then they'd quit the game and SE would lose sub money. If someone is that bad then you can try for a votekick, otherwise, personally I really am not fussed at all if someone isn't playing well. I've been in instances where the healer or tank are struggling and sometimes we wipe, but it's not a big deal to me and in casual storyline content you are 99% going to clear anyway. I know some people get really mad about wiping or taking 3 minutes longer than they are used to to finish something or the idea of carrying someone aggravates them, and I get that, but I'm just more like eh whatever not the end of the world. Taking an extra 5 minutes isn't going to ruin my day.

Anyone who is picky about the types of players they play with or who can't stand being sometimes matched with someone way below par can search for like minded players via party finder or go with friends.