I am always honored to create custom pet portraits for my patrons and the way I do it is often directly from photo references. There's a ton of debate over the use of photo references and I believe it's a balance to find what works for you as an artist. To me, photography is a tool that artists should use but not rely on (as they have for well over 100 years now). The other factor is that it's important to always paint from life as much as possible to bolster your photo references.
The other thing to remember is that a painting is not a photograph and shouldn't be compared as art forms. There are a lot of photo-realistic paintings, which to me are technically very impressive, but often have a lack of heart in them. I never want to compete with a photo in terms of accuracy (because I'll always lose haha) but I do believe I can get more feeling and heart in my paintings.
There are many techniques, processes and pathways to create a painting and however you get there is a special journey and you should use whatever tools you have access to, but having a nice photo reference doesn't mean you'll end up with a nice painting..