1 person can be millions of people online. Based on your response I don’t get the perception you understand the gravity of the problem we are facing.
"One person, one vote." There's probably an analogous argument to be made regarding speech online, ie. "one person, one account on platforms critical to democratic discourse".
I agree with you that anonymity is important too though.
Fortunately, there are ways to ensure data came from an original source without actually disclosing that source's actual identity.
This will probably require considerable mobilization of tech companies, governments, and citizens, but I think democracy and free speech online is important enough to warrant the effort.
There is no conflation. "One person one vote" was a principle formulated to ensure the will of the people is known, and that entrenched powerful interests cannot undermine this will by having more voting power than the average person.
"One person, one voice/account" has a similar rationale behind it. Technology is a force multiplier. The human mind gives more credence to things they hear/see repeatedly and from multiple different sources. This is a somewhat robust heuristic only when they are actually different sources. The "powerful interests" here are those with the knowledge to broadcast their message widely under multiple different aliases. This is why social media is such a problem.
If a particular platform is shown to be important to democratic discourse, there's a compelling argument that that platform should have rules ensuring the authenticity of the people's voice.