If it works well for them that's awesome, but that signup stinks of elitism for me. "You can't do some simple calculus? You must have nothing to add to the discussion."
To be fair, if you can't do calculus you have no business consuming bandwidth of their quantum random bit generator. It is a limited resource (they have a fixed bandwidth at which the random data is produced), so it makes sense to limit the availability.
And if you get a problem that is too hard you can refresh a few times until you get an easy one.
And if you get a problem that is too hard you can refresh a few times until you get an easy one.