Personally I like to make it a point to break this rule from time to time to reduce this pattern.
Thanks, that's very helpful. You make a good point about comments like "cool project!" not being allowed, which could cause the overall sentiment to feel skewed negative when it might actually be well received. That said, it can feel noisy and unhelpful to see a thread full of empty comments, so what if we had a thumbs up button or something that people could use to register "cool project" ? Maybe not practical, but just thinking through the problem a bit.
It's a weird dynamic to have in a web forum, where people are essentially engaging in text-based conversations, but casual, emotive speech is discouraged because that's what Redditors do, and every keystroke brings us closer to Eternal September.