There's some excellent insight here. Creative work does not get the same respect as other professions, and creative artists are somehow expected to work for free in the beginning of their career for the intangible "exposure." I think there is an important distinction to be made here however. I may be wrong, but you state, "If you cannot afford to buy their art ... merely using their work and linking it can drive sales." This almost sounds like you are justifying piracy as long as someone promotes a work. It may not be what you meant since it was written a little vaguely, but I just wanted to point out that this is the wrong approach. Youtubers I believe differ a bit from this. Yes they should absolutely link to the work, especially since many of them profit off of using the work, however they are ultimately selling their own brand and commentary/parody of another work, which would fall under fair use.
Just some thoughts. Thanks for your post!
RE: How You Can Help Solo Artist, Developers etc And Why You Should Help Smaller Creators