A “broadcast this comment?” prompt after successfully submitting a comment, even a toggle that’s default-on, would solve this elegantly IMO. I have no idea why they don’t do it. Facebook was once great at understanding that people don’t want to draw outside attention to some things that they technically do in public. They seem to have ceded that ground to Snapchat entirely, which is a painful sentence to type.
Not to beat this hackneyed drum to death, but: it’s because you’re not the consumer—you’re the product. They have armies of data scientists optimising their holy interaction metrics to death. They are incentivised to wage a holy war for your eyeballs, and wage a war they will. Every last base point is priceless at their scale.
Every single pixel, every possible user story, everything down to the very last detail is optimised for user interaction.
If you ever find yourself wondering why they missed something: they didn’t. It’s intentional.
Even if everything they do today is intentional and quantitatively optimal (color me skeptical), the site is still changing as the world changes and their user/"product" characteristics change.
The intentional things they do tomorrow will be different and may address issues like users becoming apprehensive about interacting when it's not clear who will get an e-mail saying "Psst... Hey... We thought you should judge what User has been up to..."
That sounds like a great way to overfit. I do not know exactly when it was, as it was in a lot of ways a "boiling frog" process, but from ~2010-2015 I felt the shift from "user" to "product", fully at the expense of enjoyment and user experience.