Are T-slot tables necessary and is it worth paying more for steel?

They have different profiles of all different widths and heights, they are customizable and you can order them pre-cut to length and they have 3

40 Series T-Slot Extrusion · 40 Series T-Slot Hardware · End Mills & Collets End Mills for Aluminium · SurfacingSlab Flattening Bits · V

aluminum tslot They have different profiles of all different widths and heights, they are customizable and you can order them pre-cut to length and they have 3

aluminum t slot extrusions made for M6 Nuts 100mm grid to attach the plate compact construction TolerancePrecision: +- 0 01 mm 200 mm