1. This is a Linux-friendly laptop for the most part, but it's still built with Windows as the primary OS (and the only one you can get preinstalled). When you're building things with Linux kernels in mind, it's easy to pick current hardware that supports Linux optimally (see also: every Chromebook).
2. The places where this laptop isn't perfect are _nothing_ like the problems Linux laptops had twenty, or even ten, years ago. I used a Thinkpad with Ubuntu in 2012, and it worked pretty well... but also ran super-hot and burned through battery ridiculously quickly. The Framework doesn't do that. Sure, it doesn't have amazing battery life (around 5-6 hours), but it also doesn't have amazing battery life in Windows; it's just the nature of the hardware. The automatic-brightness thing is real, but relatively minor compared to all the rest of the hardware (Wifi, fingerprint reader, etc) working smoothly.