Why is the proposed Austric superfamily not generally accepted by linguists?

The proposed Austric superfamily, which seeks to link the Austroasiatic and Austronesian language families, is not generally accepted by linguists primarily due to the difficulty of providing a solid demonstration of its validity.12

Establishing such deep genealogical connections is inherently challenging because of the long durations involved in prehistory and the resulting scarcity of reliable data. While the hypothesis was first proposed by Wilhelm Schmidt in 1906, it has faced significant skepticism and was long neglected by the linguistic community. Although some recent research has aimed to strengthen the theory, it remains a subject of debate rather than a consensus classification. Unlike well-established language families that rely on systematic sound correspondences and reconstructed ancestral forms, many broad superfamily proposals—including various attempts to link Austronesian to other groups—are often viewed as speculative.234