Sure you can. You can not post political things on social networks. They're not doing any good anyway. They're not changing anyone's mind. They're not providing depth or width to the discussion. I don't say this to be insulting, but rather a realist.
My point is that I just want to be able to discuss any topic with my followers without self-policing lest a bunch of anonymous accounts butts into the conversation and completely derails it.
What you're probably looking for is closer to a closed discussion group or mailing list than "social media", which is presently universally-readable, algorithmically-targeted, feed-based, advertising-supported, and increasingly, saturated with AI slop (which itself has replace clickbait and ragebait).
Which reminds me of Kitman's Law: Pure drivel tend to drive off the TV screen ordinary drivel.
From Marvin Kitman <https://en.wikipedia.org/wiki/Marvin_Kitman#Television_criti...>
Cited in Arthur Bloch, *Murphy's Law and Other Reasons Things Go Wrong!" (1977) p. 30.
<https://www.scribd.com/document/672553711/Arthur-Bloch-Murph...>
I want my posts universally-readable and universally-interactable (that's why I don't like the idea of locking my accounts). I also want to be able to explore the social graph — looking at who follows who, what that friend of a friend posts, etc. It all forms an integral part of what social networks are.
What I absolutely do not want is the platform having any of its own agency. I want a social network that ideally works as a dumb pipe. I especially don't want my content surfaced in front of the kinds of people who would've never found it through their own exploration.
It should come as no surprise, then, that I have a lot of faith in the fediverse.
Twitter has settings for who can reply to tweets, which are configurable per post. You can make it so that only people you follow can reply.
Why do you assume that there needs to be a purpose other than discussing a topic that you're interested in?
Politics is a complex topic. If you want to learn more, social media is not the way to do it. Well reasoned books and essays are. If you want to convince others of your positions, social media is not the way to do it. Personal relationships in real life are.
What's left?
Again, you seem to insist on an ulterior motive, completely discounting the value or pleasure of conversation. In contrast, reading is a solitary activity. Have you heard of book clubs? People read books, and then they get together to discuss the books.
Hacker News itself is all about reading articles, and then discussing the articles with others. "If you had to reduce it to a sentence, the answer might be: anything that gratifies one's intellectual curiosity."