Years ago most shoes had real leather soles and heels and when they wore down you took them to a cobbler to have them replaced. Plus many soles were stitched or tacked to the upper unlike nowadays when they`re all glued together and the soles are either rubber or synthetic. Rubber rots easily plus the glue they use rots synthetics away too.
Back in the day people used a neutral polish on leather shoes and bags in order to keep the leather supple, to feed it and stop it from cracking and protect it. That doesn`t happen now and I`m as guilty as the next person for not using a proper shoe polish on my shoes or bags. Leather is animal skin and like all skin it will shrivel, crack and weaken just like skin on a corpse (sorry for the analogy) but unlike yester year our footwear isn`t expected to last for years and where we had maybe one pair of good shoes, now we have a glut and know we can always replace them sooner rather than later.
Paying a high price doesn`t always mean high quality even though it should and mass production, poor quality leather and materials, glue and synthetic soles don`t help.
Patent leather is one of the worst culprits these days for cracking and flaking. Years ago making patent leather was very time consuming and it meant polishing real leather time after time after time with oil and it took skill to make it. Nowadays it`s just leather which is coated with plastic or acrylic to make it shine or to emboss it. If we were to deconstruct a patent bag it would be a very thin layer of leather, coated with plastic to make it shiny, then backed with plastic in order to make it thick enough to make something out of and then lined with fabric.
Patent leather is made of leather that's been coated in plastic, varnish or lacquer to make it shiny. ... (Leather with a thicker coating than patent leather is sometimes called patent laminated leather.) Often the surface is left smooth, but it can also be embossed, crinkled or crushed.