If I had to guess, it's that Apple refuses to implement very CPU-heavy JS features they don't think add much value in Safari.

I recall some feature I was using that ran in an inferior way to save power on Safari, so much so that I had to kill that feature and use a different API

I would be at least slightly surprised if Apple would deliberately hold back power-saving techniques from third party developers. It’s not like this is something that makes Safari much more appealing to users. Most users wouldn’t even notice that their choice to use Safari is responsible for their great battery life.

Blessed or not, I still end up using Safari. The improvement in battery life is too significant to ignore

It's because of the quality of Chrome. Google's focus is on features and security, with efficiency secondary. Safari's primary focus is efficiency.

Google's only incentive to make Chrome more efficient is when they start receiving heat (no pun intended) about bad performance.

Totally guesswork here, but I'd say Chrome has a lot more telemetry, profiling and tracking built-in and its users tend to use a lot more plugins, including things like ad-blockers that scan over each webpage and can be beneficial (battery-wise) or not depending on content. Safari users are more of a barefoot type. A power user is more likely to not be running Safari. And a power user may, well, prefer to sacrifice battery power to get the power they seek.

Besides, there's some precedent set in 1998 by a certain OS that "favored" their embedded browser over the competition, so I doubt Apple would want to tickle that fancy.

That's because optimizing for battery life is a stated goal of the Safari team, it's actively benchmarked

It’s mostly that they care. Chrome is designed with the mindset that it’s the most important thing running on your computer.

It's not impossible, but I doubt it, if only because very few third party applications use as much as Chrome does. The only exceptions are things that actively use a lot of CPU, like compilers or compressors.

Its been a really long time but safari on Windows was a thing and it did run a lot leaner in the background than anything else available at the time (except Opera if memory serves).

It’s entirely possible that Safari is intentionally avoiding features that make it wake up-

I doubt that it does anything unavailable to other browsers, thats MS territory, because they wanted features. I feel like safari, by contrast, doesn't want to add features.

If only the underlying engine were open source so people could see what “secret APIs” (sic) it was using…

I’ve not noticed a difference between safari and brave, so I’d say the former is not blessed.