Asymptotic freedom is the idea that at low energies we cannot use perturbation theory because the coupling becomes extremely strong. One the other hand, at sufficiently high energies, the coupling becomes very small and so we can use perturbation theory. This can all be determined by investigating the $\beta$-function.
My question is:
Why is the asymptotic freedom of quarks not considered to be a sufficient explanation for confinement?
According to asymptotic freedom: at low energies the coupling becomes so strong that quarks cannot be isolated which explains confinement. If I am right (which I'm probably not), then why is confinement still considered to be such a mystery?