Why not 'orthonormal matrix'?

https://en.wikipedia.org/wiki/Orthogonal_matrix#Matrix_properties

It might be tempting to suppose a matrix with orthogonal (not orthonormal) columns would be called an orthogonal matrix, but such matrices have no special interest and no special name; they only satisfy (M^T)M = D, with D a diagonal matrix.

Why mathematicians? WHY???