Why not just be helpful without the repetitive image?

Exactly.

Repetitive posting is spamming. Don't be repetitive and add value with each post and there is no problem.

A good question to ask in assessing any behavior is, "What would happen if everyone did it?" If everyone posted a repetitive and/or meaningless (even if individually innocuous) comment or image on every new user, the system would be destroyed not only by the clutter but by the sheer volume of comments. If every user looked at each new user and made a careful decision about whether or not to engage based on common interests, etc. and then did engage in a meaningful manner, the system would be improved. Please consider the latter.