I've never had a trainer tell me that I can't ride my horse, though I would never claim that I've gone at it alone. I have had countless hours of lessons, the patience of nice schoolmasters, coaches at shows helping me enter the right classes and navigate the warm ups when I was just starting out.
Anyone who says that they are a self made rider is lying. There are hundreds of hours that others have invested in your journey, be it by cleaning stalls, coaching at a show, giving your horse a 'training ride or two', clinics, lessons, etc.
Let's give credit where credit is due. Though some people choose more support than others, none of us have done this alone.