Dieppe's support shortfall was visible before the raid

Does criticism of Dieppe depend on hindsight?

No. The size of the force and the absence of adequate naval fire support were known before the landing, and the timetable allowed too little time to prepare that support.

A raid must allow enough preparation for its target and force size. A few hundred commandos attacking a limited objective might need only a couple of destroyers, while a much larger assault on a major target required heavier fire support. Dieppe's one-month timetable left no time to assemble the cruisers and minesweepers needed to provide it. That mismatch could be recognized before the operation took place.