Why do these rugs and carpets take so long to make according to the ad?

Câu hỏi :

Question 81 - 83 refer to following paragraph:
Patak - Ins’t your home worth it?
In business for your generations, Patak is renowned for its high quality, its vast knowledge of hand-knotted carpets, and its excellent customer relations. We deal only in genuine oriental and Persian carpets and rug of the highest quality, with detail, workmanship, value, and hand-made beauty that machine-made imitations simply cannot match. All of our carpets are 100% handmade and take months or years to complete because the knots are hand-tied to a destiny of 400 per square inch! Our collection consists of the finest-quality rugs made by Pakistani master weavers who have passed down the skill from generation from generation for centuries.
They are made of the highest-quality materials: 100% New Zealand wool with highlights of silk. Isn’t your home worth that kind of quality? Shop conveniently online at our website and search through a huge selection of hand-picked oriental carpets and rugs we have in stock! With this much selection, we’re confident you will find the carpet that’s right for your home. All prices include international door-to door delivery, which can take as little as three days! Stop by and browse. You’ll be glad you did.
81. Why do these rugs and carpets take so long to make according to the ad?