"I believe the idea is the dimple drain would catch any moisture from the walls and deposit it down to the French drain. Correct?"

Never heard of a dimple drain before, but I think your deduction is correct.

Most basement membranes are dimpled. This allows any moisture that does happen to get behind the membrane, or permiate through from the inside (vapour) can trickle down the wall and be drained away.

This feature is standard and you will find any good contractor will use a dimpled membrane, just not call it a "dimple drain"

photo of our recent membrane installation, complete with "dimple drain?"
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