DeviantArt is an art site that is no excuse at all. This is a place for artists to post their work not for random kids who don't know about copyrights to post whatever they find on google searches. There are other sites for if people want to share stuff like tumblr where you can post things (WITH proper credits/link backs) or reblog from the original artist's blog. though that said I know lots of pixiv artists hate people posting to tumblr even with credits
Just because others do it too doesn't mean it's ok and I will happily go report that one too then. Correction: YOU don't care and maybe some others don't either, but there are also plenty of others that DO care. It just shows how many people out there are completely utterly disrespectful to artists who were kind enough to share their work with the world. How would you feel if you worked hard on something and someone else just came along took it and showed it around getting praise and attention without even giving a mention of you even though it was yours?