As much as I hate the current interview process, this isn't true.

The justification foe the assessment is that the assessment is the defined set of hoops that the company who you are trying to get paid by has assigned.

Isn't that a bit circular? "This is the assignment because the assignment is this"?

That might be true, but is a different issue. It's certainly doesn't justify dishonesty.

That's a silly argument. There are many jobs at which being smart is an advantage. IQ tests correlate fairly well with being smart. Giving an IQ test could then give you a group of people that are more likely to be smart than the initial interviewing population. Assuming the job is not "taking IQ tests" is the assessment unjustified?

Seems irrelevant if the people getting the job by cheating are considered high performers getting promotions

I think you took too much from implication. TFA states that they are getting promotions. Everything else is assumptions:

1. They are considered high performers (maybe promotions are on a schedule?)

2. They are actually high performers (some people can bullshit their way through a job for years).

3. They are outperforming a hypothetical person who didn't cheat on the test and would have been hired instead of them with an honest assessment.

If an org can’t tell who is good and worthy of promotion when they’re working for them every day, they have no chance of doing so in an interview