Aluminium slot profiles

Why use expensive T-slot extrusion? - Hardware aluminum 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 aluminum extrusion t slot 3DINNOVATIONS 2020 Series Aluminum Profile Straight Line Connector, Length 100mm Bracket Fastener with M5 Screw, For T Slot 6mm Aluminum Extrusion Profile

aluminum t slot channel MiniTec T-Slotted Aluminum Extrusions Modular Aluminum Profiles For Custom Construction From Aluminum Extrusions Custom Clean Rooms, Ergonomic