Unless you are considering lower velocities that result in more drop and wind drift, the shorter BBL is NOT less accurate. In fact it is the opposite. A 16 Inch BBl is a compromise. If someone needs a short light rifle (say for CQC, room clearing, vehicle entries etc) a 16 inch BBl is worth loosing some performance, some even go less than 16" for these applications.
If you want to shoot long range etc then more BBL is worth the extra weight and length. Not because it is inherently more accurate, but because you get better velocity, and energy with its greater ability to, shoot flat, buck wind and kill cleanly at greater ranges.
For a predator application, somewhere in the middle (18-22 inch) is a common compromise.