Put a 2" loop on and then tell me it doesn't affect draw length.Yes anchor will change but so doeswhere youset the draw length of the bow.Just using an extreme to make a point.
Everything you do or use will affect the set draw length of the bow.Anchor can/will be affected also.Especially when changing release styles.
I think wewill all agree that we pull longer with our fingers than with a release,same principle,just smaller amounts.
A proper length loop will change draw VERY LITTLE,usually about a 1/4" and most can't tell the difference in a 1/4" too long or short but that doesn't change the fact that it has changed.
Let me add,most loops are too long and the 1/2" in draw length change has become a standard.