Picture aside, would that be a tray processor? Possibly 'gray market' and therefore a bit sketch for warranty support? i.e., you might have to go to the OEM that bought the lot, not AMD.
And isn't a 2600X just a lower binned 2700X? Both having cores disabled... four cores disable for 2500X, two cores disabled for 2600X. I think that's good, though, as it means it's on the 12nm architecture vs. being built on the 14nm architecture of 2400g parts.
My answer to OP is AMD does this for marketing consideration. It's even possible one or more of the OEM's insisted on a 4-core part, sans-iGPU, to support what they want with their product stack.