Sorry, but this really isn't true. Healing up a KOed character via potions is an absolute last-resort tactic. You do NOT want to do it if there's any other option.
To heal up a fallen ally with a potion you have to spend 1) a minor action (to put away any weapons you're carrying, if you don't have a hand free), 2) one, two, or however many move actions (to get over to where the fallen ally is), 3) a minor action (to draw the potion), and 4) a standard action (to administer the potion).
That's probably the best part of two turns during which you and the downed ally are out of combat. You'd better hope the DM is kind and has had the monsters move away from the KOed target, because if not they can just hammer you while you're doing it, inflicting more damage than the potion heals. On top of that, the 10 HP from the lesser potion may well be less than the target's healing surge value, and the higher-level potions cost outrageous amounts of money.
By comparison, a 1st-level Cleric can just use healing word to heal up an ally for surge value + 1d6 + their Wisdom modifier, at range, as a minor action. I think it's pretty obvious which one you'd rather trust your life to when you're bleeding to death. :)
- Saph