Integration in an apparel supply chain means different things to different buyers. The full version, meaning owning the path from fibre to finished garment along with the people to run each stage, is expensive to build and hard to justify in most situations. The partial version, meaning owning one or two stages and working with partners for the rest, is more common and usually easier to defend.
The argument for full integration is control. Whoever owns the spinning, weaving, dyeing, cutting and finishing controls the timetable, the quality at each handover and the cost base. While it is working, that control is real and valuable. When it breaks, and every stage eventually has a bad month, the owner of the whole chain owns the whole problem, including the fixed costs that continue while a line is stopped.
The argument for partial integration is flexibility. A business that owns the stage where quality varies most, which is often dyeing or finishing, and works with named partners for the rest keeps much of the control and retains the ability to move when a partner has a problem. The cost for each unit is higher, and the exposure to any single failure is lower.
The decision should follow the volume and the quality required. Very high volume with a demanding quality standard can justify owning most of the chain. Moderate volume with a demanding standard usually justifies owning one stage. Uneven volume with an ordinary standard almost never justifies owning anything, because the overhead of running production is wasted on a product better served by a partner.
There is a further consideration that rarely appears in the case for integration, which is attention. Running production is a separate business from designing and selling a product, and it consumes the time of the people who are usually best at the second thing. Businesses that integrate often discover the cost in the quality of their range rather than in the cost of their cloth.
Capital is the other constraint, and it is the one that decides most cases. Machinery bought for a particular construction is difficult to repurpose when the range changes, so integration tends to lock a business into the products it makes today. For a brand whose range evolves every year or two, that is a heavy commitment to make on the strength of a single good season.
Our own position is that of a buyer. We own no production and we work with independent mills in four countries, some integrated across several stages and some not. What we bring is the judgement of which arrangement suits a requirement, and the willingness to say when integration at a mill is serving that mill's own utilisation rather than your order.
The honest summary is that integration is neither a virtue nor a mistake. It is a way of holding risk, and it should be chosen by a business that has decided, with open eyes, which risks it would rather carry itself.