Interesting. Do we have a concrete reason why, e.g., TLP[0] falls short of the power management features offered on other OSes?
Can you expand on this? Perhaps a URL with more detail?
In the end though it is cultural and not technical. Debian will bend over backwards to make sure That One Guy can still install the latest version on his old Centaur CPU, from floppies. ChromeOS is laser-targeted for specific, allow-listed hardware platforms. If you are philosophically committed to the eternal comfort of That One Guy, the Debian way makes more sense. If you just want software that's faster and more secure, ChromeOS has the better way.
Which is a roundabout way of saying; it's critically important that we don't over-optimize for the central, happy path (just wanna browse securely on whatever hardware ya got). The most interesting things (and the most valuable) frequently come from the edge cases, which are absolutely supported by keeping an eye on the needs of "That One Guy". Unix interoperability has given us a bounty of awesome shit and I anticipate it will continue to do so.
Battery life of ThinkPad that supports Linux with TLP installed and properly configured will be very similar to Windows. And to address FUD from other reply to your question: AFAIK official Firefox builds for Linux use PGO as well, however PGO has quite less impact on battery life than what another commenter suggests.