It doesn`t work that way. Usually the history of posts is viewed in order to make a conclusion based on more information about a particular user. For example, a user has written a more or less normal post, but you aren`t sure whether to reward him with a merit. You open the post history and see how good is the work of the member as a whole. You may be able to find other decent-merit-posts and you`ll reward this member.

Another reason to view the post history is the useless, poor-quality, or even the rule breaking comment you encountered. Then you analyze the activity of the user as a whole, to decide whether to report this member to moderator. The history of his posts can both confirm that he`s a spammer (it`s here participation in various bounty, the writing of one-line-posts play the role), or else you can refute such guesses. In the latter case, you give him the opportunity to improve the quality of his work, perhaps even give advice on how to do it.

But noone doubts that good, high-quality posts deserve merits (regardless of previous activities). The history of posts comes to the rescue in a situation of doubts and hesitations.