Find their topic and press Me too on it.
It is not decoration. The boards can be sorted by it, so a request with two hundred players behind it is visible as one request with two hundred behind it - which is far more use than two hundred separate topics asking for the same thing, each looking like one person's idea.
If you have something to add - a detail, a reason, a case where it matters - reply as well. If you only agree, Me too says it better.