The rep points, as far as I know, are intended to be used as a way to distinguish regular, helpful, long time contributors from the masses. It takes more than 19 people liking something you said to get there.
It also depends on the people repping you, if I remember correctly. Depending on the rep giver's own rep, will determine how much the recipient gets.
That's why I tell people to not to get uptight when johnny 2 post troll comes on and negs 20 people... his neg reps are worth basically nothing because he has no rep power.
-Mike