Again, read my statement about the different ball ends. We agree here.
On the other item, I am not trying to argue either, you are entitled to your opinion and thinking that it does not make a difference. You also have the choice to measure or not measure your shocks- that's up to you. Your skill level may or may not be high enough to tell the difference, however equal shock lengths, at least side-to-side do make your car more consistent. This is a fact.
Whether you achieve this by using calipers or by calculating total threads showing or not is not as important, however the extra step of measuring with calipers does not take but an additional 30 seconds per shock and the result is more consistent. This is why people measure them.
Shock lengths can also be used to adjust for piston position, which is an additional adjustment that allows you to change the behavior of your car when switching directions.