Hi,
Many hurry to post the first with spam comments just for visibility, they don't even read the post.
On the other hand, as you said, they think you will not remember the comment that you read an hour ago and rewrite it so that receive an upvote too. I always appreciate those who add value to the post and engage in conversation with others. Very well said, cheers!
I have a few people who use ginabot (or similar) when I post and they are usually the first few in. As long as they add value, I don't mind rewarding them.