I think that they wanted people to use the hints, instead than just try a lot of different solutions, at least that's the idea I get from the rating system. Still, the problem was that on some occasions the first try was actually just to get what we were supposed to do, because the rules were missing some vital information or so ambiguous than one would have to make some hyphotesis. For sure giving borderline with two tries on those puzzles that gave you four or five different solutions was spot-on (otherwise one would simply try everything), but even on the others, excellent would be for those who used hints and no wrong solution, passable for a wrong answer, borderline for two or more. It makes sense.
They should have probably just have written the instructions better, then the system would be really "fair" to the player