The idea is that if you treat somebody like an employee, they're an employee, and that idea was allowed to be hollowed out. If companies participate in certain shunning rituals they're allowed to keep those same cheap employees.

The purpose of the ruling wasn't to allow companies to operate in an identical way with identical costs, just meaner. It's not even a perverse incentive resulting from the ruling. It's that we've decided that only superficial, administrative features define an employment relationship, and so long as those rituals are adhered to, the fact that you work full time completely under the control of someone for years on end is not sufficient. There's no limit to the indirection, you may not have ever met your "actual" employer.

This is not an accidental outcome, this is an efficient outcome. It could be ended by government, but for the people who pay the people who work in government, it's ideal.