Some artists get really famous for some concepts they come up with. Actually, a person might not even actually come up with a concept, but if a certain artwork of that artist gets attention, usually people will say that any other artwork from other artists that come after that is a mere copy.
Although it is important to acknowledge original artists, it's a fact that their pieces become inspiration to others. Inspiration is out there, and IMO it's impossible to say that styles are property of people. I say that because many might state that the work of Michael Rogers is a copy of previous artists, like Olly Moss. Michael's pieces are yet another example of a great geeky artist making gorgeous illustrations, and that's what counts. You may even buy some of his prints, which is great! His 'The Walking Dead" pieces are astonishing! Check out his store at Etsy for more! What do you think about many artists following the some concepts and styles? Cheers. ;)