Yeah I feel like a lot of people don't lift as much now or something if they are this anti supplement. I have a good friend who works at an NFL training facility and he has always been a fitness freak and has always trained with certain supps. I can see if you play tennis 2-3 times a week at a medium pace and that's it, not needing or taking supplementation seriously.
Pro tennis players actually take a lot of things that are far beyond what we would need. There are all kinds of things out there that help you focus, give you more sustained energy, etc. The majority are illegal, but they are being used all the time.
As for creatine. I know it works for me. You can't fake having your bench go up 25 pounds in 2 weeks..BUT I also don't know how long it works for and I definitely know it is something you should cycle. I also personally don't take it anymore. I did in the past and respected what it did for me, but I don't see it as something I need, especially as a guy who wants to stay light on the courts and not get bulky from water retention and gains.