Question for Hair color specialist

I went to a new hairdresser recently asking about highlights. She pretty much told me my hair would never be able to get blondes or highlights again because I have box dyed it dark browns, almost blacks, and that box dye stains your hair. I was shocked. I thought eventually I could do highlights or go blonde again. Is this true?? My hair is a natural dark brown. I don’t have to have it blonde but would love to have the option to change it if I want.