I don't really get the point of NUCs in this price range. They're priced like higher-end laptops, only without the portability and built-in peripherals to help justify paying a premium for the components they provide. There isn't much point in making a system so compact if it's not meant to be carried around. For something like a home theater PC or some business systems, an ultra-compact desktop PC might make some sense, but at a much lower price level than this.
What good is offering CPU performance "on par with full-size gaming desktops" if it's paired with low-end integrated graphics that will be abysmal at gaming? They have some larger models that allow for a full-size dedicated graphics card to be installed, but that largely defeats the point of the form factor. You might as well go with mini or micro-ATX then. And judging by that site's pricing for their existing models, that $1,500+ for the i7 system will likely only get you a base model with 8GB of RAM, a 256GB SSD, integrated graphics and no OS. You'll have to pay significantly more for a usable amount of RAM and storage, Windows, and of course a graphics card if you intend on using the system for gaming.
Meanwhile, it's possible to get complete, name-brand gaming laptops on Amazon for around $1300 featuring an i7-11800H, 16GB of RAM, a 512GB SSD and dedicated RTX 3060/3070 (laptop) graphics hardware, along with Windows 10/11. And that's in addition to all the other standard features gaming laptops in that price range provide, like a built-in 144Hz 1080p display, a backlit keyboard and a battery. So more portability, and far better specs for gaming than the base-model NUC sold there. Sure, you could technically configure the NUC to have better specs than one of those gaming laptops, but that's likely to bring the price up into the $3000 range.