I would like to hear the refutation because I've witnessed this myself in corporate environments. Corporate HR are difficult to deal with, they're very process orientated and risk averse, getting rid of someone reflects poorly on you and your management structure basically doesn't care if there's 1 useless person in your team. You have to put a huge amount of work in to document and justify why the person is not qualified for the job and (in my country) you've got to make a reasonable effort to find another role for them, and if you do start this process with HR it creates documentation that means no one will ever take them if they do want to transfer.

Start to end you're probably talking about ~6 months to get rid of someone and over that time you need an intense process of setting them targets and documenting failing to meet expectations. The result is that most managers are more likely to try and shuffle their bad engineers into other teams than to actually give up a big chunk of their time doing this process. Not to mention the fact it puts you in a very awkward positioning having a working relationship with the person you're getting rid of.