> Well.... If you cycle a battery between 30 and 80% its lifetime increases by almost 10x. The battery management on phones is terrible. Either the manufacturer is stupid or malicious.

As pointed out by sibling comments this is somewhat common nowadays. iPhones will IIRC default only charge to ~80% overnight, stay there, and only charge up to 100% when it thinks your normal wake time is approaching. I remember Macbooks starting to do this at least 10-15 years ago. I'm not sure well this aligns as "an obvious decision to kill batteries on purpose". Is it possible that it isn't a grand conspiracy, but instead a natural consequence of having to quality and expense of parts vs what one thinks the market can support?

The other option from your proposal of course is never to charge above 80%, or call 80% "100%", in which scenario you would almost certainly have the same sources accusing them of being underhanded and anti-consumer by "artificially limiting battery capacity".

There is obviously no conspiracy. It's common business sense to not care about battery life in a product with a 2 year lifecycle. The fact that SOME phones don't overcharge your phone battery shows that it's a business decision rather than a technology challenge.

OEMs seem to be getting better about this.

I see batter limiters in MacOS, Samsung phones, Framework laptops, Microsoft Surface devices. Now we just need to normalize it on budget devices.

Samsung seems to have added a battery care feature that will detect if your device is mostly plugged in all the time and charge to 85% instead of 100%.