I think it was to keep residents who can't get a permit here from getting a non-resident permit from FL or UT which are honored by reciprocity. But if you're a legal resident of LA you need to have an LA permit.
This is part of it. Having training in LA laws is part of it. LA permits have more requirements than some other states. The LSP (and a lot of legislators) view this as a good thing. But one of the primary reasons that you never see mentioned is that the arrest of a LA permit holder is immediately reported to the LSP permit section. The arrest of a LA resident holding an out of state permit is not. The LSP believes that is important.
All in all it helped things go well for the carry bills you guys really support.