Very interesting observation, but I think it was more by happenstance.
But that's because AMD got its APUs skewed by 1000 from the desktop CPUs with the same generation core, and jumped their desktop models from 3000 to 5000, in order to sync them up. Recall that 4000 was still Zen 2, just like 3000, except monolithic APU instead of chiplet-based.
6000 was Zen 3+ on N6, and originally meant to be both laptop + desktop. If they're not planning to do a Zen 4+, then there would be no need to skip the 8000.
There's something else going on with the 9000-series branding, because all previous EPYCs were 7000, where the last digit was the generation. Probably, they wanted to differentiate it somehow from Begamo or Siena.
I wouldn't parse it that finely, but you could be right.