Shot bands still used... limited though
I recently bought a steel-substitute for my dad's older non-steel rated semi: it specified shot bands or unslit wads only. It is through wondering why that I came by this reasoning:
To my limited knowledge shot bands are only used now with shot that may scratch or damage a barrel. There are certain brands of steel, steel-substitute and steel-mix shot that can still damage an older barrel marked for steel (or subsitutes that can scratch old, Damscus and other barrels). The most modern barrels have accounted for this I believe, but only in the last few years. As most shot cups are slit and would allow the shot to scratch the barrel as it is forced to contact the barrel only in the slits (in other words, the slits force a nice long scratch in the barrel), this allows you to insert the shot band into the cup, or use a fibre base wad/no cup wad, and not receive scratches.
Not perfect... but better than slit wads in this case.