More to do with efficiency; Russian/Soviet gas turbines tend to be less efficient than comparable Western engines. The Tumansky engines on the MiG-25/31 series of aircraft are HUGE,
almost the size of a commercial turbofan, in order to generate the required thrust; a Western engine of comparable power would probably be about 2/3-3/4 the size of it's Russian counterpart. My guess is this is due to metallurgical reasons; I believe our high-temp refining processes are more developed.