The Supreme Court of the United States has ruled repeatedly that anonymity is protected by the First Amendment, specifically because anonymity enables free speech. A person who does not speak because they've been cowed into silence is deprived of their rights. "Anonymity is a shield from the tyranny of the majority. … It thus exemplifies the purpose behind the Bill of Rights and of the First Amendment in particular: to protect unpopular individuals from retaliation … at the hand of an intolerant society." (McIntyre v. Ohio Elections Commission.)

Thanks for pointing out an interesting aspect of US constitution.

It however doesn't change what I said.

When fighting political causes, anonymity doesn't help - Gandhi or Rosa Park or Martin Luther King continue to inspire us today because they faced injustice and tyranny head on. They have provided us with an effective template to fight against injustice and assert our rights.

Fear is often the reason behind anonymity, and that doesn't bode well for any political cause. Even Gandhi, who inspired non-violent politics said that he would prefer if people chose violent politics than giving in to fear or cowardice ( https://www.mkgandhi.org/nonviolence/phil8.htm ). Moreover, politics on internet is even more fraught as even foreign powers can hide behind anonymity to interfere in the politics of other nations.

The claim I was responding to is, "In a democracy, there is no reason to hide behind anonymity while fighting for a just cause."

What I'm saying is that there absolutely are reasons.

This is also not a binary proposition. In a group of activists you can have some people working anonymously and some people working out in the open.