The finishing is necessary, you must to see the tissu when it come from the loom, before the finishing! Finishing is also for to set dimension stability of tissu, no only for this, also other raison!
This days use other substance, is some restriction, much much year before some times use thing like formaldehyde for part of finishing!
Are you saying that finishing can make the yarns more stretchy and resilient? That was the original question raised.