A DDOS is an attack because it removes resources. Other people having opinions that disagree with yours isn't removing resources from you.
Whether it's newspapers or a town square, there have always been people who have been loud. Loud does not mean right. It also doesn't mean you need to muzzle the people who are loud.
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.