As a writer, the promise of "exposure" is the equivalent, and often people profit from work done for free, with the understanding that somehow it will lead to something else, that it rarely does. When young writers finally begin to put a value on their time, that is when people finally begin to take them seriously. Fortunately, in writing there are more lower paying gigs available to cut ones teeth on, so free work is mostly unnecessary, but entire sites like Huffington Post are making millions off of free labor. There is an entire slave class of creatives in this world and I think you nailed it! Don't stay there any longer than you have to, and work not to take advantage of any other artist, give fair exchange. Nicely put.