Like on Titan Quest, where at least one quest per act granted one skill point on completion per difficulty, meanwhile on Grim Dawn, you have just one quest per difficulty that grants a skill point.
The game gets really stingy on skill points once you get to 50+ and most skills requires at least 12/16 points to max, so it would really help if we could at least a few more extra skill points by completing certain main quests, like one for killing Cronley and one for killing Karroz.