Public dislike counts were opportunities for brands to own up to their ambition for authentic engagement. This is maybe the main thing lost here - without putting this at stake, and with full moderation powers on their video comments, brands basically only have a veneer of authenticity at this point. There's not as much at stake for them anymore, very limited downside / reason to care.
Facebook said it lowered engagement iirc, same reason why they removed likes count on Instagram, it reduced engagement, people posted less if they feared being judged by the number of likes.
Hiding dislikes is something Brands want.