In high end custom guns, it is rare but in factory hunting rifles it actually happens quite a bit.Have you ever seen a barrel wear out from flexing before the rifling? Properly designed steel parts usually have life cycles of over 10^8 load cycles.
The definition we used in the data of wear out means that before the chamber, lands and grooves are worn past the point of having to rechamber or replace the barrel, the barrel loses accuracy. It happens with #2 and #3 barrels mostly but can happen in other contours and rifles due to steel used or build quality. The harmonics change to the point where the signature changes (the point at which the bullet leaves the barrel within the whip) where with the same exact load may shoot a sub moa group one day and a +2 moa group the next.
True, it is something most shooters won't see in a hunting rifle, sometimes PRS style shooters see it. So from a practical hunting and a weekend shooter standpoint who will never put 1500 rounds through a rifle, it may not be as relevant but from a materials, technology and capability standpoint, ill take carbon over steel anytime.