I won't comment at this stage on the commonness or otherwise of amyl, but I'd like to clarify that it is far from being 2nd last on the list of words in order of how often they were played. If you tick the box in the top right corner labeled "Show all?", you will see about 60 rare words that were found by fewer players. It was the least played "common" word, though.
By default, the solution view does not show the rare words that you didn't play. If you see dalt quite often, Les, it's probably because you play it whenever the letters are there. Others, who've never played it, would probably have been completely oblivious of the word's existence (until now).