An upvote, like, downvote and dislike system has been suggested and discussed multiple times.
If it would carry no significant weight, then it isn't really necessary and would just be abused as everyone would be allowed to use it without earning it. The merits system is actively stopping spam on the forum.
I believe this can also help reduce the rate at which people spam the forum through unnecessary comments.
I do not see how it can reduce spam as spammers rarely go through posts and really have no desire to appreciate quality content, they are only concerned with increasing their posts counts and fulfilling bounty requirements.