In a democracy, the community determines policy. Votes are orthogonal. If the community leaves when they disagree, by definition everyone that is remains agrees with the policy, making it a democratic policy. The friction to changing instance is very minimal, so it’s a good indicator of people’s opinions.
The first sentence was a response to you asserting voting is essential to democracy, which is false. The rest of the comment was a response to you not accepting Nemo@slrpnk.net’s argument.
If you can’t find an instance you agree with, and you have a mass of people who agree with you but are collectively too lazy to create a new instance, you would communicate your stance with words. Lemmy has a system for leaving text statements. You seem to be familiar. But there’s no mechanism to force the instance operator to obey you.