Yes, the approach discussed here does give the author a stronger voice, but calling it unilateral is extreme. Comment rendering is influenced by a variety of signals. The inspiration for the OP was to explore if existing mute data/UI could be modified to achieve a net benefit in a very simple way (immediately).
What does your ideal “main window of Steem” look like? Does it cater to prospective users by showing the best of our community? To creators by providing an engaging and productive experience? How are posts and comments ordered? How is spam and abuse addressed?
Spam is addressed primarily at the blockchain level. Without question it has vastly improved since RCs and is hardly a huge problem at this point. I used to get dozens of spam comments on my posts (either my rare personal posts or burnpost), now I get a small handful. Even those often get downvoted (and hidden by UI) by others or by anti-spam efforts like mack-bot before I even see them. I think my experience is typical.
As far as abusive (in the sense of harassment), I think muting by the reader and potentially by the reader subscribing the curated mute lists is a sufficient remedy.
I don't think posters need or should have a much of a special right to curate/block/hide replies their own posts on a fundamentally shared platform. To the extent they're able to do this it should be less than absolute (and subject to community disagreement), for example by conveying some moderate bonus virtual SP to their downvotes.
Communities could change this dynamic, especially to the extent they shift to rewarding their own community-specific tokens and not global inflation. That becomes more of a "my house, my rules" situation and communities could set all sorts of rules on this (of course, more richness in this regard would be significantly harder to implement).
Spam has never been less of a problem on Steem than now, and with free downvotes upcoming, we may see that abusive (in the sense of harassment) may meet with a similar fate. At a minimum I would wait to see how free downvotes affect things before assessing anything.
Taking a deeper dive, I agree that the spam situation is not bad, aside from a few concentrated pockets. I do wonder if part of it is decreased usage. Free downvotes will certainly help, especially if there are crowd-sourced and crowd-driven downvote programs. As far as I can tell, efforts to neutralize spam/blatant abuse are led by a small number of people.
It would be great if simply sorting comment threads by pending payout would produce the most useful result. But in practice, (a) many decent comments get no votes, (b) a few low-value comments get some votes, and (c) some insightful comments are downvoted far below 0.
Increased curation rewards (and interest in the platform) could lead to more intelligent automated voting which would help smooth out the difference between (a) and (b). There's a history of trying to solve issues with more complexity, where a simpler solution would suffice.. at scale.
Curated mute-lists could be part of a solution, though I'd imagine UIs picking a default mute-list for guests would be a further source of contention.
They may be (though some of this is probably the larger efforts being more visible) but by far the biggest improvement was simply the switch to RC which cut spam by some very significant percentage overnight (my guess would be 80%-ish).
This could be an example of solving a problem with an arguably more complex system, but one which was well thought out and had broad application (unlike many of the tweaks which were more reactive and impulsively made in the past, but had the effect of layering on unstructured complexity in a more harmful way).
Anyway, I do think we should assess the effects of HF21 which at this point we can only make rough estimates ranging from very limited to profound across the platform.