the way in which lords in early Christian Ireland asserted their social status and exacted surplus was primarily through the exaction of hospitality from their clients, rather than from taxes or rents.

Your use of the word 'extracted' is misleading because this was a two way street - the céile [client] gained a number of benefits from the overlord, be it Taoiseach [chieftain] or Rí [king]. He could use the overlord's cattle or land to provide for himself. Wealth could be increased through clientship. The céile also gained support in law from the Taoiseach who in fact in most cases were kinsmen. This was all overseen by the Brehons and by Brehon law.

Even in the lower céile - there were two levels of clienthsip - had advantages in their position. If after paying the rent on the property for 7 years, usually cattle rented to them from the chieftain, they owned the property on the death of the overlord.

This all made the overlords not as secure in their position as kings in the rest of Europe. This is a point well made by Irish historians and one that I attempted to clarify on this thread.