It cannot work, being conquered and early allies in the steppe would mean these subclades would have also have equally spread to places like spain if we go with the steppe theory. This isnt factual, r1b is super strong in Western Europe with nonexistant/irrelevant and probably recent r1a to boot whereas v13, j2a etc are strong in South Europe in differing regions. This smells of a separation not a unified movement
For me, either r1b started in Spain and spread out killing off/outnumbering i2 and g until they hit a brick wall in i1 North Europe, j2a Greeks, v13 etc South Europeans and also r1a in steppe
OR
R1b came out of steppe for some reason without any r1a input, managed to push i1 out the way moving them further north to proceed west killing/outnumbering i2 and G but hitting a brick wall in South Europe which had tribes of peoples who came from West Asia
You answered it yourself, these are internal steppe people's divisions. That's why you have R1b in the West, I1 in the North, E-V13 South East, R1a East and so on. E-V13 did barely survive but made it back from its refuge, most likely in the Northern Carpathians. Compare: https://www.eupedia.com/forum/threads/30814-Where-did-E-V13-originate/page18?p=614316#post614316