The former doesn't make much sense in a distributed system where we expect to have multiple clients--and, preferably, no dominant one!--as there is no reason for the people you are restricting to opt in to that restriction.
> B) Make it so that YOUR FOLLOWERS don't see somebody else's reply unless they click a "hidden replies" button. Their post will still be visible to their followers or someone looking at their timeline.
Like, for this latter use case, if I am following you, I am buying into your frame and am often am going to agree with your moderation choices on the people who reply to you, so it actually makes a lot of sense to me that I would accept your ability to hide replies I "shouldn't" / "wouldn't want to" see.
Meanwhile, the only recourse to be heard for the person whose reply was hidden is to do so to their own audience; this not only seems fair, but strips them of the power they were trying to "steal" from you when they replied to your post in the hope of gaining access to your audience.
> A) Make it so YOUR NAME and YOUR POST doesn't appear attached to a post that somebody else makes. Their post will still be visible to their followers.
However, this former use case does not have the same structure: if I am following someone else and they talk about something you said, but now I can't see what/who they are talking about, I'm just going to get annoyed, as the goals of this feature don't align with the direct user of the client anymore.
At best, this just leads to people using workarounds, as the recourse is too powerful: anyone--not even merely the quoter--can add a reply with a screenshot of the post and a permalink through an external link shortener. At worst, it leads us down the dishonorable path of people demanding client DRM :/.
It sucks, because I was kind of excited about BlueSky actually caring about distributed incentive issues in a world where they were not the only client; but, this is the kind of mistake that people get goaded into making when they build a distributed system and start to assume centralization.
...and like, by the way: this feature is also inherently dishonest, as, even if it is documented how it works, a lot of users aren't going to understand it, and so they are going to assume they have a safety net in place that doesn't really exist in the protocol.
This honesty issue is similar to the way Snapchat claims people won't be able to (at least secretly, though I remember the original claim to be stronger) save the photos they send. Of course, people often can secretly screenshot your photos--such as using jailbroken devices or even merely a second camera via the good ol' analog loophole--but people send riskier photos because they trust the feature to protect them.
And yes, I totally understand that Snapchat's feature sort of works and maybe is better than nothing?... but, it only works due to continual effort Snapchat invests--from both their engineers and lawyers--to enforce the feature by embracing DRM, implementing user behavior profiling / banning, and sending legal cease and desist notices to alternative clients.
I hope (but no longer can assume) that BlueSky won't (or can't) ever go to such lengths; and so, in some sense, the feature is even less honest, right? :/ Even if the feature "sort of works", the power only comes from "pretty much there is only one client everyone has", and so the incentives are broken.
If I were building this, I would have done the exact opposite: if someone "quotes" you, there should be a copy of that content stored on the quoter's end, so that it is still visible even if the original is deleted... but like, that copy would be trivially editable, so no one ever treats previews as truth.
You have to implement it like that, as it has to be functionally equivalent to the analog loophole version of the feature -- the one where the quoter just attaches a potentially-forged screenshot of the post along with a link through an external shortener -- in order to align everyone's incentives.