One of the best levers many of us have is public forums, so this commenter is doing something great - enforcing the idea that the government should be changed in thousands of readers' minds. Once an idea gets enough traction, it often can turn into actual change. You are only reenforcing the fatalism you seem to criticize.
Colordrops is correct: comments matter because they help shape public opinion.
Dustingertz is also correct: governments & political parties have published processes for changing & enforcing policy. Citizens who read the docs & use those processes can achieve a lot.
