He who is harry newton said on Wed, 27 Dec 2017 17:05:03 +0000 (UTC):
Fair enough observation but the Materials Science experts seem to be
inferring a different take on that same sentiment, by stating that Apple
batteries were sold with intolerable (and unadvertised) performance decay.

They "clearly came with intolerable performance decay." says The Verge.
https://www.theverge.com/2017/12/21/16806582/apple-battery-slowdown-science

Apple basically admitted today they permanently chopped CPU speeds in half
because they were trying to secretly mask defective batteries that they
didn't want to pay for in-warranty claims.

December 28, 2017
A Message to Our Customers about iPhone Batteries and Performance
https://www.apple.com/iphone-battery-and-performance/

They desperately try to convince Apple gullibles that all batteries require
the need to be secretly, drastically, and permanently throttled (to half
the original CPU speeds) with this clever marketing document posing as an
engineering white paper.

iPhone Battery and Performance
https://support.apple.com/en-us/HT208387

Basically, what they say is that all batteries degrade but only Apple cares
enough about its customers to secretly, permanently, and drastically cut
the CPU performance in half.

The rest of the manufacturers simply replace defective batteries under
warranty. But Apple didn't want to honor the warranty claims.

Even now, they're *still* charging the customer $30 for what amounts to a
defective battery. After the end of 2018, you're ****ed again.

The phones affected after iOS 10.2.1 a
iPhone 6,
iPhone 6 Plus,
iPhone 6s,
iPhone 6s Plus,
iPhone SE,
iPhone 7, and
iPhone 7 (after iOS 11.2)

The secret is never to update iOS and this wouldn't have happened to you.