I can understand people trying to do this for one reason and one reason only - they only have one toon who runs shroud and they are so excited to get their first greensteel. If you're a part 5 dropper then its your problem that you need to craft in part 1 or 3, not the party's. The only crafting that should be done in part 3 is crunching the item (Amrath ftw). Part 1 should be done after the raid unless, like in part 3, all you are doing is mixing the shard with the greensteel.
Don't understand these concepts? Don't be shocked when someone grief's the bejesus out of you. Two wrongs don't make a right but one wrong and one right don't make a right either.