But once they know two paradigms well enough, the "pure vs impure" question becomes a real question in its own right Yeah... "once they know," which is after t

But once they know two paradigms well enough, the "pure vs impure" question becomes a real question in its own right Yeah... "once they know," which is after their time and effort has been spent and the opportunity cost has been incurred. Investing time and effort in learning something is, indeed, an effective way of finding out if the investment is worth it, but since you find out after the fact, it can't inform the decision to make the investment or not. Also, somebody who was hired for their knowledge of one paradigm and is currently working productively in it, as is frequently the case, does not need "cover" for not knowing a different paradigm.