And its related to the design of the game. Verant coded a game where numbers weren't going to be vital. Level 1 Shaman buys Strengthen. In the main for at least 33 levels, Shamans are asked to buff and the only thing that is doing is adding to downtime. It's a no-win situation.
Shamans are the king of buffs.
But for the majority of your life they are a pointless waste of resources that people expect. Often, the Shaman guides break the class down much close than three levels. And there is a lot of justification for that. The role of the Shaman can change greatly at each spell rank as they balance their strengths against weaknesses. However, I've found that there really are only three portions.