Don't worry, these arguments happen, have happened, and will continue. Ham radio for example has the saying, "The only thing two hams can agree on is the third is a fool." The only difference is that text divorces empathy from the discussion.
Best way to help, if you don't think someone's idea has some potential, ignore it. Trying to explain why you think it won't work or worse, shouldn't be done, only makes a person feel prosecuted. Text comes off devoid of compassion and often makes the contributor feel attacked. Even in person, it's hard to pull off kind rejection. Often, people given no support in an effort will grow to understand there is no desire for it and give up. If they do end up persevering, power to them! Maybe they're right and you don't see it. People will band around things they believe in.
