This might be because the small globule these spiders could produce would dry out rapidly.

All spiders produce silks, and a single Spider can produce up to seven different types of silk for different uses.

An individual projecting microscopic tube in the spinnerets from which spiders produce silk.

The spider extends its abdomen high in the air and produces a droplet of silk.

The spider, which is about an inch and a half long, produces the silk through tiny nozzles in the base of the feet.

Maybe a spider produces a peptide that inhibits blood clotting.

Each spider produces from one to four sacs with perhaps over a thousand eggs inside each.

Any one spider can produce different kinds of silk from different spinnerets.

It depends on many factors including kind of silk (Every spider can produce several for sundry purposes.)

It would take 27,000 spiders, each spinning a single web, to produce a pound of web.