>>50759541>71242577_p0_master1200.jpg>master>jpgThat's partially why. People post samples, and there's also lossy jpg compression to take into account. Gotta go to the source to get them at their highest quality.
Then there's always the risk the images will just get deleted, either by the archives/sites hosting them or by the artists themselves going on a self-purge for whatever reason. Nip artists do this alot for some reason, so many pokemon artists have purged all their shit for little to no reason