I should also think that libertarians should be in support of private people deciding not to support companies or people that support causes they disagree with. That's an excellent example of people's freedom of action.
I don't think that's really the problem. I think it's just because Reddit and Facebook are too large to work, period - sort of what Kirkpatrick Sale was trying to get at in his book "Human Scale". Global systems of humans connected and interacting are probably doomed to this regardless of what mechanisms are instituted, unless those mechanisms limit in some way the local size of the interaction.
I agree with you that sheer scale is the primary issue, but for a particular reason: these systems are all prime targets for malicious actors intent on manipulating people on a large scale.
As a liberal, not a libertarian, I would say that's a bit reductive.
People should have the right to express their political beliefs. The fear of cancellation and potentially losing their job etc isn't conducive to freedom of thought. Yes you individually may not agree and may choose not to support them, but here we have people actively calling on others not to support them, and condemning those who would choose to carry on engaging.
It's very divisive, 'you are either with us or against us'. That is far from any kind of liberty.
Punishing others, because they don't enforce your values is anathema to me.
Basically what is being suggested is that if I believe in democracy and freedom, I should be ok with an elected police state. It should be obvious that I can be pro democracy, but anti bad things that come out of that process.
I don't think it would be hypocritical for someone to support freedom or some other value, by removing freedom, or contradicting that value. I support freedom of speech, that doesn't extend to allowing others to lie, especially in the name of removing others freedoms. That doesn't invalidate my views or values.