Steem is for content, in general, not just articles. There are tons of stuff under the #photography tag, there are even some competitions and stuff, and the mobile app SteepShot to ease the process of pushing photos into the Steem platform.

On the technical side of things, the Steem blockchain is indeed only meant for written text -
but written text does of course include links, and Steem works quite well together with IPFS. There is steepshot, daudio, and several other applications/websites where one can post content on IPFS and link it up and receive rewards through Steem.