Hmm, I think they can add... but I'm not sure how they can recommend ingredients or products that are holy grail / worth a try / risky for combination skin in particular 🤔 maybe that's why they chose not to include.
That aside, I don't really use Picky's Match rating system to decide if the product is suitable for me or not... everyone's skin is different so even classifying products as suitable for dry/combi/oily skin wouldn't be my main deciding factor (only a rough guide!)