There is a significant difference between HN and real life; in real life, there are both a limited number of participants, and you are more likely to be interested in what each participant thinks. But consider a very large group, like hundreds of people, in a room. One person gets their turn to speak, and merely says "I agree with the previous speaker" and leaves the podium. Did this unknown person contribute meaningfully to the debate, or did they just senselessly waste everybody’s time? It’s obviously the latter, and it’s the same here on HN; nobody knows who you are, and merely agreeing or disagreeing without backing it up with arguments is a waste of everybody’s time.