The biggest problem with the take home tests are not people who don't show up due to not being able to finish the assignment, But that those people who do, now expect to get hired.
95% people don't finish the assignment. 5% do. Teams think submitting the assignment with 100% feature set, unit test cases, onsite code review and onsite additional feature implementation still shouldn't mean a hire(If not anything, there are just not enough positions to fill). From the candidate's perspective, its pointless to spend a week working and doing every thing the hiring team asked for and still receive a 'no'.
I think if you are not ready to pay 2x - 5x market comp you shouldn't use take home assignments to hire people. There is too much work to do, and receive a reject at the end. Upping the comp absolutely makes sense as working a week to get a chance at earning 3x more or so makes sense.