This is just my opinion, but the short answer would be no.
Unless you are specifically in some kind of contest that prohibits photo textures, or have a client that is asking for no photo textures, then this is art. There is no cheating in art. In my opinion, it’s all about the final results and not the process. Otherwise, we would still be stuck in the stone age in just about every area.
If it’s a tool that you can use, and it helps with what you are trying to do, then I’d say it’s just as valid as any other tool in creating what you are after.