Why is Khoisan considered a loose language grouping rather than a proven language family?

The term "Khoisan" is considered a loose typological grouping rather than a proven language family because linguistic evidence fails to demonstrate that these languages share a common ancestral origin.12

While these languages are often grouped together due to their unique use of click consonants, they exhibit profound differences in vocabulary, sentence structure, and word formation. Unlike established language families—such as Bantu or Indo-European—where shared structural features are inherited from a common ancestor, the Khoisan languages lack the necessary evidence to confirm such genetic relationships.12

Conventional comparative methods have failed to identify regular sound correspondences or shared grammatical innovations that would allow for the reconstruction of common roots. Although some researchers have used "mass comparison" techniques to suggest potential links, these findings remain controversial and inconclusive. Consequently, linguists generally use the term "Khoisan" only to describe a group of languages that share certain phonetic features, rather than as a classification of a genetically related family.12