Sure, but IR35 creates the opposite problem to that. It encourages you to treat them as actual employees, and makes it risky to do otherwise.
The “doom” referred to was the idea that contractors would simply be done away with. Clearly someone who is on a rolling six-month contract cannot easily be done away with. The incentive to make people into contractors is lessened by IR35 (and the recent changes presumably make it even more unattractive).
The people it’s bad for, if I understand correctly, are those who actually want to be contractors, who companies may prefer to be employees or not have for them.
Yeah, that’s what I’d expect. It’s disruptive but not the permanent destruction that it is inevitably characterized as by the affected businesses. Still sucks hard for the individual contractors, of course.