Neck bow is not only a tool to adjust fret-buzz.
It’s even more important for overall playability.
Straighter is not always better. If you use thin strings,
like 0.09, you might get away with a really straight neck.
But using 0.11, 0.12 or even 0.10, some relief is preferrable.
This because it makes for better bending, and cleaner tone.
A reasonable relief allows the strings to vibrate freely, and thus
sustain and intonation will be better, not to mention better playability
for bending and vibrato. There is no “true” neckbow, perfect for everyone.
The relief should be adjusted according to musical style and preference.