smells like a system to get around covering folks under qualified plans.
sounds like such employees are for all practical purposes leased employees
Under Code section 414(n), a leased employee is defined as a person who provides services:
To a recipient company pursuant to an agreement between the recipient company and the leasing organization,
On a substantially full-time basis, and
Under the primary direction or control of the recipient company.
https://www.irs.gov/retirement-plans/employee-plans-compliance-unit-epcu-leased-employees