It 100% applies if you have mirage to read, very little to no mirage to read on cold days. the super fancy scopes have narrow depth of field so to can focus in smaller increments between you and the target so you can read the mirage better. It can tell you what the wind is doing between you and the target, wind flag at target only tells you what’s going on at target. When it comes to wind you want as many data points as possible. Most scopes now and days should be able to focus in 5-10 yard increments out to 100 yards. However flags every 10 yards would be MUCH easier to read since you don’t have to mess with the parallax wheel, pretty sure most won’t want to touch the parallax wheel once you get it dialed.
Edit: mirage is usually for long range spotter to read for the shooter, not sure it’s useful for bench rest.