You wonder why this is becoming more prevalent as of late? Because the amount of twinks in the game is increasing. 49 Twinkies leave at the end of the WZ to keep from getting xp. I'd venture to say filling in late in a wz is a direct result of this, not someone simply DC'ing.
Not denying this happens, but when I said I had backfill to scoreboard happen to me twice in the last 3 days, I was referring to 50s pvp.