We can also determine that with a chronograph.
Sure you can. But i would think you'd want to see it on a target as well.
You can have decent groups at 300yds that have wider velocity swings than I'd choose for my loads. I prefer a chronograph for many reasons.
That's maybe because 300 yards isn't "long range".
No one said they don't use a chronograph. use one all the time and have been since the first one's became available. Don't you do more than one thing when you work up a load, like shoot it at distances? As in:
1) chronograph
2) shoot at distance?
What is so hard to understand?