Although I'm not sure why crown and pavilion angles are even being brought into this discussion, that's not an accurate statement for crown and pavilion angles...
A difference of 0.5 in crown and pavilion angles is actually quite significant, as well as whether the angles are complementary. Can easily mean the difference between AGS 0 and AGS 1 in cut grading, and it can definitely be seen through a scope. E.g. using the default angles in the HCA tool of 34 crown angle and 40.5 pavilion angle (which gives a HCA score of 0.4 and Excellent grades in light return, fire, scintillation and spread), an increase of 0.5 in both to 34.5 and 41.0 gives a HCA score of 1.7 (and Excellent grades in light return and spread, but only Very Good for fire and scintillation), a decrease of 0.5 in both to 33.5 and 40 gives a HCA score of 1.8 (with Excellent grades in fire, scintillation and spread, but only Very Good for light return). Conversely, and which is why people always talk about crown and pavilion angles being complementary, if you decrease crown angle by 0.5 but increase pavilion angle by 0.5, to 33.5 and 41, HCA score is 0.9 with Excellent grades in light return, fire, scintillation and spread.