It is still helpful to be heard and minimize harm.
Voting does not accomplish that! Voting will NOT make you heard and voting will NOT minimize harm. Your insistence that it does accomplish these things is what is harmful.
Telling people to do useless things saps their energy away from doing things that actually are meaningful like organizing. Voting is used as a tool by the bourgeois to get people to think they “did their duty” politically, so they can relax and not worry about having to do more even though “more” is still the bare minimum (voting is less than bare minimum). You have been duped by the bourgeois. Smarten up.
A major part of it is because those who do mount any kind of actual resistance that has any potential for being effective, they get murdered and disappeared. E.g. Black Panthers, or the original leadership of BLM before it was coopted by liberals. Any genuine leftism in the US has been effectively eradicated by outright murder, intense anticommunist propaganda campaigns (targeting every segment of society from elementary schools to popular media control to even workers unions themselves), and direct infiltration and dismantling of leftist organizations of any size. This society is practically built around a pathological individualism that neuters any potential for mass action. Our culture has been cultivated to only accept rightward expressions of political dissatisfaction, with no room for or even basic understanding of leftwing organization.