Thanks for the clarification guys. Here was Fritzes response, confirming as above:
The holes in the pot support section are for "tertiary air" flow to the flame.They also direct this airflow against the upward slope of the bottom ring that the wall of the pot support is spot welded to, preheating the air a little. With a very large flame, this additional air flow helps to reduce the tendancy to produce soot and helps the fire to burn more cleanly. With a smaller flame from Esbit I doubt that they contribute to an efficient burn and you are probably correct that they are more of a liability than an asset.
But the stove was designed primarily to burn wood. You might notice that when burning wood as a "campfire", even when overloaded, with pieces of wood burning within the pot support ring, the fire is still relatively clean burning, thanks to the inflow of air through these pot support holes.