If we are going to conflate "like" and "helpful" then there is no point in having such a button since it becomes meaningless. On the other hand, if we are to have a "helpful" button that actually means "this post contains helpful factual information" then that could be useful, especially if there was a way to view a large thread that only showed posts rated "helpful".

I fear this poll and thread has already conflated "like" and "helpful" and hence the votes and comments are only making the issue more confusing as people are talking about different things as if they are the same.