It makes no sense that brushing prolongs the life of a suit. My suit jackets have worn out by rubbing at the elbows and the suit trousers at the seat. Unless you work in a sandpaper factory where significant quantities of abrasive particles have permeated into the cloth, it's difficult to imagine how odd bits of lint that would otherwise have been brushed away would have any significant effect on abrasion. In fact, if anything, the abrasion caused by regular brushing would far outweigh the abrasion caused by the non-removal of odd lint particles. However, raising the nap to reduce shine once abrasion has taken place is the only thing that can be done at that stage whether by using a brush or other abrasive surface.
In the same way I would also expect that regular shoe leather conditioning using the finest creams and wax polishes won't make the blindest difference to the lifetime of the leather before it cracks. Conditioning of leather can only affect the very top surface of the leather which is a tiny proportion of it's depth. Quality leather is your best defence against cracking not quality care or quality polishes.