I don't think locking low level players out would fix much. I've had low SR players call in decent vehicles and high SR players do nothing. A lot of it depends on the person playing. What I've suggested in the past is for 343 to have better descriptions so people know that it's a difficult REQ heavy playlist which isn't for the inexperienced.
Edit: Didn't realize I already mentioned this in my first post, lol.
Edit: Didn't realize I already mentioned this in my first post, lol.