Good point but if this went mainstream it could be considered a requirement the same way a good growing company behind a fledgling startup will never get away with hiring people full-time unless they supply a healthcare plan and other standard benefits most employees at respectable companies receive, to the point there is no chance they could not be competitive with out them.

And that's the thing really. They could be required to have them, so then it's just a matter of which ones are competitive to the employees.

I would love to apply to a company, ask who their third party HR is and say oh man that one SUCKS and everyone knows it. Sorry, gonna take a job at this other company who had external HR with much better rankings, the same way I might for more competitive healthcare plans or benefits between to equally competitive jobs.

Of course companies do not want to spend money on things like 401k matching healthcare and the otherwise but they will if enough companies do it to the point they look sketchy if they do not only provide these benefits but provide these benefits through respectable third parties.