I think now (personally) that, not only does the person seriously admire the artist, but they are learning methods from them.
Like how to make muzzles, paws, and so on easier to draw and then later change it to their own style.
It's really common... But I think the above statement is true. Though, there are other reasons.
Like to be a neusince (did I spell it right

) or to just be a theif. You never know...