Why do most scholars reject the proposed Ural-Altaic language family?

Most scholars reject the Ural-Altaic hypothesis because it lacks evidence of a common ancestral vocabulary, which is essential for establishing a genetic relationship between language families.1

While these languages share structural similarities—such as vowel harmony, the use of suffixes and postpositions, and a subject-object-verb word order—these features are widely considered to be the result of areal convergence and language contact rather than shared descent. Furthermore, researchers have been unable to demonstrate reliable, systematic sound correspondences between the Uralic and Altaic families. Because these structural commonalities can arise independently through long-term interaction between neighboring groups, they do not provide a valid basis for grouping the languages into a single genetic family.12