Because you're claiming that "modern humans" came into Europe from Africa about 30,000 years ago and replaced the Neanderthals, with only 1-4% interbreeding. So, when we look at the fossil record, we should see Neanderthals up until 30,000 years ago, then starting at 30,000 years ago, the fossils should look the same as modern Europeans.
As the pictures I posted clearly demonstrate, that is not what we see in any way, shape, or form. Can you pinpoint, on my skull chart, where "Neanderthal" ends and "human" begins? There should be a clear demarcation.