One should remember that for example, the mechanized and armoured forces of the German Army were the creation of a small group of “tank enthusiasts” such as Guderian, who frankly admitted their intellectual debt to Fuller and the other
British
“tank enthusiasts” of WWI and the interwar period; not the German General Staff as a whole. The difference was that Hitler soon forced the army leadership to allocate resources to armoured warfare, whereas Fuller and those like him in the British Army had no such advocate, or at least not one who could overcome the fanatical resistance of the “Equine Tammany Hall” who in Fuller's phrase, dominated the senior officer corps.
The Reichswehr remained a highly conservative organization, philosophically and militarily, but not to the extent of obtusity. It is to the credit of the German senior officer corps that having seen the armour advocates proved right in 1939/40, almost all of them became convinced and cooperative, unlike the ____________s who continued to predominate in the British high commands, who despite being decisively defeated in 1940, and having the lesson repeated several times by Rommel in the desert made a sort of perverse virtue out of muddling on in the usual way as though refusing to adapt to circumstances, at the cost of uncounted thousands of lives and very nearly the war itself, was evidence of some sort of moral victory. Not for nothing did Fuller remark that “there are two truly conservative institutions in the world: the Catholic Church and the British Army”! Not that other armies in the Anglosphere don’t have such people as well, to say nothing of the Frenchicon Army, though Fuller thought them very quick to adapt new ideas so that may be an unfair comment.
The point of all that is, that the high command of the Reichswehr were not the types to be hypnotized by mechanization and automatic weapons to the exclusion of sniping, nor did they have any philosophical reasons for abandoning the lessons of the Great War; quite the reverse in fact. Their highly developed training and instinctive thoroughness predisposed them to use whatever was useful, and sniping which every officer who served at the front in WWI would remember was highly effective, would be as much a part of that as mortars, machine guns etc. If anything they might have been predisposed to exaggerate its effectiveness, given that trench warfare was almost an ideal scenario for sniping. Armies are perpetually and inevitably preparing to fight the previous war as we know.
As for the poverty of the Soviets in the 20s and 30s, they were well able to find money for what the regime wanted, even at the cost of millions of lives. Sniping is a force-multiplier, perhaps the most potent conventional one to this very day in terms of efficacy and economy. That alone could explain much of the Soviet interest.