The XP needed to level in DDO is about 10 times more than in the PHB at higher levels and 5 times higher at lower levels. I think I know why they used one digit higher number but it doesn't make it that much more difficult to calculate for balancing purposes.
In the Kobold Ringleader example from earlier you encounter "2-3 dozen kobolds, 1-3 hobgoblins, and an ogre." for 1200xp. For a lvl 1 DDO character that would be about 1/5 on the way to leveling.
For a lvl 1 pnp character that would be like getting 120XP out of 1000 needed to level.
When by pnp rules he should be halfway to leveling.
Of course because this encounter would take much longer in PnP with everyone waiting for their turns etc, so it would be annoying to only be 10% on the way to level 2 at the end of it.
So when I say "I look in the DM Guide to see how much I should have got from those encounters" I do take into consideration that I need 5-10 times more encounters in DDO.
So it's only for encounter vs. encounter not for the actual number.
Out all of these posts, nobody has mentioned any implications of dividing the XP per character more like it should be. You would still get less from soloing and still get more from groups, it would just be more balanced.