The real story - No Rights Employees ("employed for tax purposes")
The real story here is the creation of the "employed for tax purposes", No Rights Employee (NRE).
Once the big companies realise that they can convert their permies to NREs without attracting any HMRC trouble (which they couldn't do with contractors) then we're all up the swanny. A hundred years of unions negotiating working conditions swiped away in a heartbeat. Entire sites, divisions and departments closed on literally the same day as the bosses announce it. People getting fired for getting pregnant - or fat, or arriving late to work. You name it - all possible with NREs.
For public listed companies especially, NREs mean less head count, and that means they can report a higher "earnings per employee" in their accounts. That improves their share price, which improves their chances of (foreign) investment or takeover. The odd contractor having to take an "inside IR35" role might sound innocuous enough, but when you realise NREs are the wedge that will end up selling off British businesses and the assets they own, it starts to look slightly different.