As a matter of fact, you CAN keep walnut from adsorbing moisture.
You can greatly reduce the amount of moisture that a walnut stock will absorb,but unless you can seal it 100% and keep it sealed 100%,it will absorb moisture.Any nick scratch or ding will break that seal and let moisture in to the stock.
I realize you've had bad luck with stocks but when properly free floated, bedded, dried before finishing, and pillar or bedding block, you CAN hunt with wood from now on without having to worry about the stock causing the barrel to walk.
Why would you bother with pillar bedding,bedding blocks or free floating if you can keep walnut from absorbing moisture?If you can be 100% effective at preventing the walnut from absorbing moisture and either swelling or warping,these procedures are totally unnecessary.I think that you will agree that if you really want the prettiest rifle,full length bedding without the unsightly free floating gap looks best.In reality,these procedures are usually carried out to try to prevent a change in the point of impact when a stock absorbs moisture.
Of course you might be talking about factory rifle stocks only.
My response was to the previous posters statement about "quality" firearms,and the rifles that I mentioned were in fact factory rifles.