Quite a number of official military scope mounts used tapering dovetails. The German WWII Short Side Rail mount was tapered, as was the prototype G.41 mount. The Russian PEM side mount was tapered, also the US Neidner mount (equals the USMC mount) for the Winchester A5 mount was tapered. Not only the French used it for their own mount on the APX, but also for the SOM scopes they supplied to Argentine. There might be quite a few more which I can't remember, but obviously since carried also into WWII it might not have been that of a bad design.
The already mentioned German WWI "Semi Turret" called scope mount by Goerz was based on the same principle, but not with a dovetail but a circular base with cone-shaped walls. The Germans made the rear foot adjustable lengthenwise, to make it interchangeable (the rear was only a metal cone with a locking arm). See the pictures here for the rings on the scope of this mount:
scarce complete WWI german sniper scope - Wehrmacht-Awards.com Militaria Forums
The US solution from Neidner was interesting in this term, that it used inverted dovetail mount for recoil to lock the scope in position. This would also work with the bases of this rifle. So I suppose they copied the mount of the US with their own "advantages". But on the other hand this wouldn't make that much sense, with inventing new scope bases.