Agree with you 100% , and this is exactly why my primary reference prior to breaking the shot is my rifle bubble level, not the crosshair. My eyes suck, and i'm not confident I can consistiently achieve "plumb level" viewing the crosshairs only repeatedly. centering the bubble is a more consistent pre-shot condition. Shooting 600 yds on a grassy dirt firing line I constantly have to keep adjusting my rifle for perpendicularity as my Atlas bipod has the capability to adjust cant, and what can happen is the rifle recoil bounce can drive one bipod leg deeper into the ground than the opposite leg.You’re correct up until you put a level on the turret cap. This is a moving part that isn’t directly connected to the reticle. The bottom of the turret housing is better but still there is no guarantee that it’s in perfect relation.
Spin your turret and check level every 90* I’d be surprised if they all showed exact same thing.
Also looking level and being level are two different things. If I eyeball level my reticle always looks slightly canted to the right but a plumb bob don’t lie.