I have had PPO high deductible health insurance for 14 years, and I have been able to see whatever doctor I want whenever I want.
Obviously, I need to pay out of pocket until I meet the deductible, but it all counts toward the annual out of pocket max and I get the negotiated pricing between doctor and insurance company. After I meet the deductible, however, the insurance still pays for a consult for anyone I want to go see. Not necessarily for any procedure though, without justification. But that applies in any situation, PPO or not.