Due to the detachment of these family clans, ordinary people had no access to them. Hence, they were called reclusive family clans, not because they were really hidden.
As for Zhou Kui and company, they came from large families, but their families were from the Jing state or the surrounding small states. Those kind of families just occupied a small province of a state.
A provincial family clan had no way to compare with the reclusive family clans at the Divine Kingdom level.