It all depends, but regional carriers do offer lower shipping costs and faster delivery for online brands. Merchants that have a high volume or concentration of customers in a specific area can take advantage of partnering with a regional carrier to save on cost and speed up delivery.
However, keep in mind that working with regional carriers can push you below the volume discount threshold with major carriers. Also, managing multiple carrier partners can add complexity to logistics operations, and there can be some tech limitations, from order routing to label generation.