I did interview, and found the tests far too difficult and not remotely like anything I've ever hit in 20 years of doing software development. Everything was rather computer-science-algorithmicy, and there was no ability to ask for clarification on aspects of the puzzle-questions that seemed ambiguous. Couple that with somewhat short time lines, and it was frustrating.
In my 20 years, I've never not been able to ask a client or PM or end user for clarification on what they mean, but what I took from toptal is that you'll be expected to work under those conditions.
It certainly weeds people out, and the whole "we'd rather weed good people out than let bad people in" mentality is probably understandable, it just rather felt like a "one size fits all approach".
Interestingly, looking at their site now, I read "we do not tolerate sub-par work or poor communication for any reason." Except, of course, when taking their entrance tests - no communication for clarification there. FWIW, tests were from codility.com