I had a similar experience. My LFG post was "Oryx Hard, Please be experienced and know multiple roles." Somehow I got 3 kids in my fireteam. I was feeling in a good mood so I decided to keep them. Keep in mind it took about 10 minutes to get a group together. We start Oryx and I see one of the kids going through their menu. They die. Whatever, everyone grabs ammo and wipes. 2nd attempt. Kid is going through his menu again and then dies. He says, "I'm trying to find my Malice." Whatever. 3rd attempt. We're gonna tether the thrall now since someone has their super built up. Kid says, "I'll draw them to the center." He stands right next to a group of distant thrall and dies as they smack him to death. The kid says, "Sorry, I thought you were gonna tether them!" Then another squeaker joins the party chat and in a high pitch voice says, "Are you doing Hard raid?!? I'm so jealous!!!" Then the kid who's on our fireteam that keeps dying says, "Take my spot, I don't feel like doing this anymore." And he leaves. The fireteam disbands. Completely wasted 20 minutes of everyone's time, for what?? After that...I have decided that I will never party up with kids again. Ever. From now on every LFG post will include "NO KIDS". I encourage everyone else to do the same.