Purpose of Pastoralism for Pure Nomadic Factions (non-Pahlava)

[kingaveryyt]

I am currently in a Sauromatae campaign, enjoying harassing infantry-reliant nations and close to wiping out the rival Saka from the map. Anyway, as the title states, I don't see the usefulness of installing Pastoralism in Nomad or Mixed province regions. Since the purpose of playing nomadic factions is to use mainly horse archers/heavy cavalry compared to settled nations, the only gains I see for Pastoralism are walls, roads, and weak infantry while losing the ability to create horse archers. For the non-nomadic/mixed regions, Allied Settlements would be much more useful since I will be able to use the Local MICs, which will provide better quality infantry in which the Sauromatae really need while losing the ability to use noble cavalry. Unless there's something that I don't know about, should I be building Nomadism in all nomadic/mixed regions and Allied Settlements in the non-nomadic/mixed regions?