Not sure why people are saying Mythic+ score is irrelevant. It's perhaps the most relevant thing there is to judge a strangers competence outside of knowing what they're like from past runs. It's a direct indicator of experience in different keys. ilvl, sure, that's no indicator at all. Mythic score definitely has a use.
Nowadays more than half of my groups fail as I'm trying to pug to get my score up (+14-16) because the leader will invite at least 1 person that's crap and will ruin the run. Some +16's will go smoother than a 13. It's just luck.
And not to be horrible but EU has a disadvantage because of language barriers. I've stopped grouping with Russians because I've yet to find a skilled one.