The main problem however, is that curation is so well rewarded. Some large stakeholders often don't care about what they're voting on, only that they get their 10 full upvotes a day done to maximise their returns.
I have already commented on the high curation rewards but this allows me to explain myself further. No one cares for firing out 10 full upvotes to maximise curation because it does not work that way. Spreading your mana to 100 posts works as well. There are few ways to change your curation ROI. You can vote after the 24hr window closes but that is trivial to avoid. Basically, two major factors remain:
You can self-vote (circle-vote). The extra returns are technically author rewards but they were generated via curation.
You can vote on stuff that attracts downvotes and lose out.
Number (1) is easier with big votes but it is up to the community whether they care or not. I am going to discuss the non-cheating part here.
The funny dynamics is created by (2). If a large stakeholder is ready to downvote overrated stuff, your best play to maximise curation is to spread yourself thin not to stand out (the larger your account is, the more important).
Consequently, a single grumpy reward-disagreement oriented account can push large accounts to distribute rewards wide (which I already claimed to be positive). All it needs is to survive.
It has to be large enough to be relevant, it should not be used for posting (for reasons beyond getting zero author rewards) and it should spread their own upvotes thin to minimise DV damage from top accounts defending the status quo (not to waste too much earning potential on its large heap of HP). Lots of work but it is doable.
None of this fun game is longform vs shortform. Accounts acting on this division act based on opinions and preferences, rather than curation maximisation.