This Wikipedia article states in the introduction
Conductivity is proportional to the product of mobility and carrier concentration. For example, the same conductivity could come from a small number of electrons with high mobility for each, or a large number of electrons with a small mobility for each. For metals, it would not typically matter which of these is the case, since most metal electrical behavior depends on conductivity alone. Therefore mobility is relatively unimportant in metal physics.
As we know, conductivity does depend on mobility $$\sigma = \rho \mu$$
where $\rho$ is the electronic charge density. The sentences in bold state the electron mobility $\mu$ is irrelevant when dealing with metallic conductors because the exhibited electrical behavior depends solely on the conductivity $\sigma$ of the material in question.
Why is mobility 'irrelevant' in metal physics? Even though conductivity, which is a very important parameter in metal physics, does depend on this irrelevant quantity?