I often shy away from matters regarding downvotes because they can be quite controversial and also can earn you a place in some people's bad books (which is not so much of a problem to me these days).
Downvotes are necessary, even on layer 2. We cannot ignore that people exploit the loopholes in the reward system and sometimes it is not intentional in the case where one is been autovoted, which in my opinion isn't a bad thing per see. We have so demonized autovotes and failed to see its value.
There is a lot to curating than just rewarding quality posts which is subjective. For instance, I am aware of a newbie initiative that is structured to help committed newbies grow their accounts faster. The upvote on their content isn't based on its quality but more on their effort and commitment to the chain.
People reward content, personality, relationships, etc This is a social norm even on a decentralised social platform
As I have said in the past, what makes a post rewardable is the value it adds to others, and value in itself is subject. So the best thing to do would be to let people decide through upvotes and downvotes. However, the power structure on layer 1 doesn't make this a fair game--it has never been.
Layer 2 solutions seem to be the preferred option for many people, but it does have its cons.
In a nutshell, I don't think the system is structured to be fair. If it was, we will all have equal stake and votes, which isn't even ideal. So that's the dilemma.
Layer 2 is more flexible.
You actually don't have to downvote to remove rewards because tribe leaders can mute individual posts and deny rewards to individuals, depending on your set up.
It's less messy. And in that regards, downvotes becomes optional or even purely for reward disagreement.