All of my rifle scopes are in MILs. I also have a Vortex spotting scope and purchased the extra eyepieces which have reticles graduated in both MILs and MOA.
So if I am spotting for someone that has a scope in MOA, I put in the corresponding eyepiece.
So when it gets down to where the rubber meets the road, I don't care what someone prefers for their scopes.
On the other hand, I have one pet peeve. That's the people who have a scope on their rifle in MOA and are spotting for a person with a scope in MILs, or vice versa. They don't bother to ask what the shooter's scope is graduated for!
Then they start spotting for the other person and tell him how many clicks, up/down, left/right he needs to correct for.
The worst example was when I was shooting my Sharps 45-70 with black powder loads. Normally, when there is a breeze, the smoke clears enough where I can see the impact down range.
This particular day was one with zero wind. So when I shot, the smoke lingered in front of me and I couldn't see the impacts on or about the target at 600 yards.
The other person was not shooting but looking through his riflescope and giving me corrections in so many clicks. I don't know if his scope was in MILs or MOA. I couldn't convince him that I needed the corrections according to target dimensions. The fact that I was shooting with 150 year old style sights meant nothing to him.
For example; come up half a target and left a target. If you have ever used a vernier sight on a Sharps you would understand that "clicks" (even in MOA) doesn't help me.
I ignored him.
There are four things in life that I cannot stand and not necessarily in this order:
(1) Cold coffee
(2) Wet toilet paper
(3) Dancing with a woman that leads
(4) Someone who cannot spot!