How is it elitist to use all available information to make a more informed decision about who to invite.
You’re the one who is preferring higher item level because:
Anyone can get a mythic kill and score some gear from there. Just because they have a high itemlevel doesn’t mean they’re good in a M+ situation with a small group.
Experience and player skill >>>>>>>>>> ilevel. Just like it has been since Vanilla and every game before wow. Better gear is just another factor that helps improve the odds.