[Lazy_Perfectionist]

There are several common reasons people go for less dominion.

Bad scales that they want to outrun.
Cheap, quality priests of at least level 2 (Ctis), and somewhere specific to put the rest of their points.

As an interesting fact, priests can raise your dominion above your pretender's natural level. With a temple and t2 priests preaching, you may see this, but with t1 priests, you're out of luck, unless you have a ridiculously bad dominion scale.