Early M-38, then later M-44, and M91/30 laminate stocks were first issued without wrist bolts. I have examples with both types. I've also seen wrist bolts installed on some M91/30 and SVT-40 stocks, when refurbished. That modification is rare on birch stocks. Wrist bolts were not used on Czarist period rifles. Not even the Finns used wrist bolts on their birch stocked Mosin Nagants. That must say something regarding the strength of the wood. Solid birch, beech and walnut stocks will crack if exposed to enough abuse.
The Soviets during the Great Patriotic War were quite conservative regarding scale of equipment issue and very practical and minimalist in design. Post 1945, laminate stocks were becoming more common, especially during refurbishment of inventory. Don't forget the massive loss in men and equipment of all types during the war plus the destruction of major industrial centres. Laminate wood is very practical when ordinary birch wood is in short supply.
If there was nothing wrong with the design, or the production methods of laminated wood, nor any feed back from field use indicating a flaw or failure at the wrist from recoil stress, why install a reinforcing bolt, if not necessary?
It wasn't done from 1891-1950's for birch wood stocks on millions of rifles and carbines.