Pretty flawed logic, if you ask me, considering this same argument could be used for Madara's strength Ei "How are people using Madara for Sharingan feats when he has the second most chakra after Kaguya?" That doesn't make any sense. Of course a dojutsu's power will change depending on the user. That's not a reason to dismiss her ability with the Byakugan, otherwis you'd might as well dismiss her feats with the Rinnesharingan and anything else she has. Point is, she displayed the Byakugan at pretty high levels, levels enough to destroy Sasuke' Susano'O casually.
I won't deny that that might be the case, but given it's appearance and characteristics, and the fact that it's even compared to the Hyuga clan's Air Palm, it's not illogical to say that the Byakugan plays the biggest role in the attack. Plus, the Perfect Dojutsu bit may just as well be referring to the fact that the Rinnesharingan can provide back up for the attack. After all, I never saw the Rinnesharingan in use when she was using her Eighty Palms attack.