Training function matters in cable machines because the machine is only valuable if it supports useful strength work, smooth setup, and repeatable progression. A cable stack can look versatile, but the workout quality depends on pulley height, resistance range, attachments, stability, and how easily the user can move from one exercise to the next.
A strong cable machine helps people train pulling, pressing, core, accessory, and rehabilitation-style movements with controlled resistance. A weak setup may still have cables, but it can feel awkward, slow to adjust, or too limited for the routines people actually want to perform.