due to the nature of arch and its rolling releases, it tends to get bleeding edge updates/features rather than having to wait for a major update to iron itself out then get rolled out. If you're a gamer for example, if Valve fixes a bug in the gpu driver, then Arch would probably get it asap (especially given that Steam OS is arch based)

It's just another distro that has gained a following more because of some perceived superiority than any truly practical reason. If you're new to Linux I wouldn't recommend it.

What's good about it is that if you know what you're doing you can install only what you need and keep your system small and tidy. Also, since it's a rolling distro, updates become available really quick and sometimes some of the updates introduce optimizations (meaning more performance) or better power consumption. And finally of course Arch has also an amazing wiki, they have hands down the best Linux documentation along with Gentoo, and they even have a page about Thinkpads: https://wiki.archlinux.org/title/Laptop/Lenovo