Leather products are a mystery wrapped in a riddle. I worked in the leather products industry (mass market and high end) for years and can attest that "reality" is an illusion, and virtually anything claimed by a brand/manufacturer is disputable or an outright lie. For example, the term "genuine leather" means precisely the opposite (as an industry term) than the public thinks it means (TL;DR its not genuine). I wont get into it, but you can research that to be amazed and disgusted simultaneously.
That said, I have zero faith in leather products that arent hand made in a country that has high manufacturing standards (such as full-grain hand crafted goods made in USA). A watch band like this leather link (I own two LL fyi) is a finely designed composite of a bunch of different materials to make a band that wont fall apart easily with heavy use, with its thin and gracile construction, implanted magnets with little margin around, and painted with a PU edge. There may be a layer of "top grain" leather on the very surface, which is the very top of the animal skin (most durable, patina-able and costly), but its razor thin at best, and non-existent at worst. How can this be? Well, the lower layers of skin can be painted and embossed to appear as top-grain leather (the user can almost never tell).
Lastly, regarding the specific issue of Patina, leathers can be treated or painted with a variety of petroleum or plant based chemicals to resist wear and patina. This is in the best interest of a company beset by uneducated customers (apple users) and goes a long way towards preventing returns. Apple likely decided to add more durability based additives and materials to keep this $100 band from failing with use. The casualty of that is patina, as patina is a mark of vulnerability or oil-absorption capability, that will over time disrupt the glues and materials that went into the complicated stack of thin materials that make the LL band.
