Good luck hiring and then firing incompentent people (and there are many such "programmers") at scale. At least by making interviews hard you're not putting families at risk which you would by hiring people to fire them with pretty high odds.
I was tring to give hawk_ the benefit of the doubt by not assuming that's what was meant, because it seems like a very bizarre concern to me, given that hawk_ was talking about "incompetent people".
Incompetent people put their own families at risk by trying to work in an industry where they're incompetent. It's not the responsibility of employers in that industry to provide for the families of people who can't do the job. It's really a bizarre concern to be worried about the families of fakers. Moreover, how would it be better for the family of a fake for companies to not hire them at all, as opposed to hiring and inevitably firing them? In either case they'll be unemployed ultimately, but at least if they get hired and fired they can pick up some paychecks, so that's actually better for their families, if that's what we care about here.
The quotes on incompetent was missing. If someone's set at a place and proves to be "incompetent" in another setting their family is better off if they never switched the job in the first place. Hiring someone with 5/10+ years of experience for example and firing them after trial is a worse outcome for most people than not having had them make the switch in the first place if it was avoidable.
(1) Competent programmer who isn't a good fit for a particular job.
(2) Incompetent programmer, the "can't code, can't even write a for loop" bogeyman that seems to scare everyone.
Coding interviews — whiteboarding, take-home projects, and the like — are intended to filter out (2). But they aren't good at filtering out (1).
(1) can always occur. There's not a great way of avoiding that until they actually get on the job. Of course it's unpleasant to fire somehow who doesn't work out, but I don't see how take-home assignments are supposed to help here with (1). Whereas the (2) people shouldn't be in the industry at all, and they're lucky to somehow scam someone into giving them a job, but the industry should not be financially supporting scammers or their families.
I'm personally not convinced that (2) is as big a group as many people believe it is.