I would suspect, that some people just get frustrated with posting after awile.
I realize that the "critical' people are few and far between.
But I have seen where people have made a post, and have had others say whats wrong with what they have built etc.
Theres nothing wrong with constructive critizm,but we need to realize how to present the thoughts. Just like in real life.
I am sure that when someone has an idea, or a post of something they built, that they would welcome comments.But also see how they could be discouraged from posting, knowing someone will 'tear' it apart.
Just my thoughts...and observations.
Al