Why should you give credit to the artist?

Many times on FB, when the artist is not reported, some people comment against in manners that are quite rude. This is not a good approach, you attract more dislikes than approvations.
When it comes to such a delicate topic I think the best way is to remind that giving credit benefits everyone, not only the artist.
Always assuming that the one that is sharing art can extract the name of the creator, not always it's possible! So we should be a bit less nazi about.
CREDITS FOR FONT:
Coolvetica font by Typodermic Fonts Inc. - typodermicfonts.com
CREDITS FOR ICONS:
Computer icon by Jules Renvoisé
Raising hand man icon by Marco Fieseri
Hat icon by Marcus Michaeis
Happy man icon by Abraham
Stressed man icon by Shreya Chakravarty
Confused man icon by Andrew Doane
Walking man icon by Yamini Ahiuwalia