Are you implying that Neji can perform the same feat? Because that's what I'm getting?
Not even. Again, OP said full potential, not potential from select characters while ignoring others.
If you want to keep insisting Kaguya is an unfair comparison (even though we're talking about full potential here, not VS matchups), don't bring up Sasuke and Madara since they're incarnates. Don't bring up Shisui and Itachi since they're prodigies. Don't bring up Obito since he's 50% Hashiroids.
Who are we left with? Freaking Izuna and Fugaku at best, who fall below Hiashi in terms of feats.
Not to mention the Sharingan is innate to humans (manifesting in Indra first), while the Byakugan is innate to aliens, and its only the aliens that can push it to its full potential (Tenseigan). Yet it's wrong for me to pit the Byakugan's original wielders against the Sharingan instead of the diluted human Hyuga?