Because perk was introduced to for balnes otherwise unbalancing the arena.
Are we just assuming that
unbalancing the arena is the right criterion for perking an aircraft? Or does it actually stand up to scrutiny...
Clearly, if only 2-weekers flew the Tempest, it would not unbalance the arena. Then by the
unbalancing the arena criterion, the Tempest would not be perked. Now, very few of us would accept this result, and so by following the
unbalancing the arena criterion we have found ourselves in a contradiction, and therefore the criterion should be abandoned.
This seems to be the case with the Spitfire16, but in a less extreme way.
We found ourselves in this muddle because
unbalancing the arena depends way too much on the quality of pilots who fly the aircraft.