I have heard that use of counterweights in crankshafts also help with bearing life because "counterweights reduce peak main bearing inertia loads". Is this true? If its true how does that exactly help reduce the loads on the bearing, i couldnt quite understand it.
Yes, because the counterweights are there to reduce or elimination of vibration.
If you consider the vibration is caused by a movement of the crank against the bearing then it can be considered it is causing damage.
Engineers calculate the offset rotating loads for the rotation of the crank and design the counterweights accordingly.
Then if the power strokes overlap then the engine feels smooth: consider a v8 or v12 compared to a 4 cylinder. Of course a 4 cylinder can have a heavy flywheel to help this.
An inline 6 is known as a smooth engine as it is in balance for primary forces.