Keep re-rolling stats until you get awesome ones? Do these DMs also let players reroll attacks until they crit and then reroll damage until it's max?
I feel like everyone who says stuff like this should be forced to present the character sheets of all the PCs in their groups for the last ten years so they can be audited by the Game Police. It's funny how everyone is all "Oh I make them keep what they roll!", and then when you see actual PCs from their games it's strangely all 17, 16, 14, 14, 12, 12-type arrays...
Personally, if we roll (which we didn't, generally in 3E, and never in 4E), each player generates 10 "sets" of stats (usually using a spreadsheet or java program), then picks one of those. We disregard total outrages as well as rubbish stats, though (fr'ex, even before this, with normal 4d6-drop-the-lowest, my brother rolled an 18, 18, 18, 17, 17, 16 array, so we made that PC into an NPC, because damn...). Certainly produces much higher results than point-buy or similar, but makes for characters people get very attached to, in my experience, which is very good for the game.
If I wanted to play "most of you will be dead..."-type D&D, I'd be playing DCC (which is a fun game, in a different way).