I mostly agree, but attending any interview is
also doing unpaid work in your free time, and often takes a comparable amount of time to the sort of take-home assignments used for recruiting.
I think the reason why take-home assignments tend to feel more unreasonable is the asymmetry. If I attend an interview, it's costing a pile of my time, but it's also costing a similar pile of time for multiple people at the company where I'm interviewing, which gives me some reason to think that my application's going to be considered seriously and therefore that the effort I'm putting in isn't going to be totally wasted.
Whereas a company can hand out a take-home assignment with no effort at all, so the fact that I've been given one doesn't indicate that the prospective employer sees me as a serious prospect or that there aren't hundreds of other candidates in the same position as me, so it's no guarantee that my chances of getting hired aren't miserably low, so there's more risk that I'm wasting my time.