T-Slot Aluminum Extrusion

TSLOTS Aluminum Extrusion Manufacturer extruded aluminum tslot 30 Profile 4 Slot 30mm W x 30mm H Aluminum Smooth Extruded T-Slotted Bar Extruded T-Slotted Bar Fastenal Sku: 0961287 extruded aluminum tslot So one of the industrial plants I work in has scrapped a HUGE amount of aluminum T-slot extrusion and I have free reign over picking through

extruded aluminium t slot My question is - why use expensive extruded aluminum T-slot? I mean, for a CNC router it makes sense because you need sub-millimeter