You're talking so much about depth in Russian skating and how no other country can compare - Ok, let's do a direct comparison of Korean, Japanese and Russian Senior Nationals last season. Keep in mind, all three countries allow some juniors to take part in their respective nationals.
15th place:
- Japanese nationals: Ibuki Sato, 21 - 171.86
SP: 3Lo+3T, 3F, 2A (BV: 31.33)
FS: 2A+3T, 3Lo, 3F<, 3S+2T, 3T, 2A+2T+2Lo, 3Sq (BV: 54.42)
- Korean nationals: Siwoo Song, 14 - 158.28
SP: 3Lz+3T<, 2A, 3F (BV: 30.56)
FS: 3Lz+2T+2Lo, 3F+2Lo, 3Lo+2T, 2A, 3Lz, 3Lo, 2A (BV: 56.61)
- Russian nationals: Ksenia Gushchina, 14 - 171.62
SP: 2A, 3Lz+3T<, 3Fq (BV: 29.19)
FS: 2A, 3Lz+3T<, 3F, 2A, 3Lz+1Eu<<+3S, 3F+2T, 3Lo (BV: 59.73)
So, yes, Russia has impressive depth - Much deeper than Korea, not to even speak of the US, which ended up not even having 15 women competing at nationals (Ok, two skaters withdrew after the Short, but that's not making much of a difference). But Japan? Japan has decently comparable depth, even if the peak is not as high as that of Russian women's skating.