Although you are right to be skeptical of this claim because near-native competency is always possible, L2 competency (learning a language as a foreign language

Although you are right to be skeptical of this claim because near-native competency is always possible, L2 competency (learning a language as a foreign language) will always be less than L1 competency (native). For instance, there are grammatical constructions with very low input frequency about which native speakers have strong intuitions, which L2 speakers will not have. The difference in L1 and L2 intuitions may be remarkably subtle, often semantic/pragmatic, but you don't have to work in the linguistic community for long to come across them.