Although that seems like a valid reason, consider how many justifications have been used throughout history to scare people into submission. “There May be cheaters out there” is of the same form as “there may be <insert statistically unlikely thing> out there, so you’d better <unnecessary overreaction>.”
If there is data to support that most people are cheaters, that’s fine. But at Matasano I believe the statistics were ~30 candidates who were invited for an on-site interview after a take home test, and ~30 happy hires.
The on-site interview was also mostly a formality; the fact that they could do the work was enough to all but guarantee an offer.
And when you reduce it to those terms, it seems ludicrous that the world should be any other way. You can either do the work or you can’t. And if you can, nothing else should matter.
There are other counter arguments: what if someone is a huge introvert and not suited to working in a team environment? Bring on the introvets, I say. You won’t regret it. The most talented coworker I’ve ever seen was also someone who had stammering problems and would barely talk. But he was very nice, and much more skilled than I was at the time.
You don’t know someone until you work with them. And if they’re a bad hire, it’ll work itself out within the first month. It’s far better to deal with a possible cheater than to miss out on a skilled, solid hire. The latter makes or breaks companies; the former are just a temporary thorn.