Any knowledge of why certain conferences dont have lines for their respective games?

[Magnificent]

NEC, SWAC (usually), MEAC, Great West...

Is it by ruling of the governing body of the conferences?
Or is it perhaps because linesmakers find these conferences to be too inconsistent or not enough eyes are on them?
Maybe prone to point shaving due to their small stature and level of interest?

I know there is a reason, I'm just not sure of the exact reason!

Anyone with this knowledge?

I know they are small schools and not many people would actually care to wager on these (mostly), but there are plenty of people who would I'm sure if given the opportunity.

[Crate Mayne]

I always wondered that too, and always just assumed because Vegas wouldn't get much action on them... Which disappoints me, because there's some teams I'd love to bet against (America East - Binghamton University!)