  We prove that conformable ``fractional" differentiability of a function
$f:[0,\infty[\,\longrightarrow \mathbb{R}$ is nothing else than the classical
differentiability. More precisely, the conformable $\alpha$-derivative of $f$
at some point $x>0$, where $0<\alpha<1$, is the pointwise product
$x^{1-\alpha}f^{\prime}(x)$. This proves the lack of significance of recent
studies of the conformable derivatives. The results imply that interpreting
fractional derivatives in the conformable sense alters fractional differential
problems into differential problems with the usual integer-order derivatives
that no longer describe the original fractional physical phenomena. A general
fractional viscoelasticity model is analysed to illustrate this state of
affairs. We also test the modelling efficiency of the conformable derivative
using a fractional model of viscoelastic deformation of tight sandstone, and a
fractional world population growth model.
