I really don’t get the point behind micromanaging and willingly using half of the battery capacity.
So let’s say that we charge up to 80% and use it until 20%. You are using 60% of the capacity with a brand new phone.
1. The battery is still aging
2. You are already using only 60% of the battery, that is equivalent to a 5-6 year old phone
3. Since the battery ages anyway, the “60%” that you are using is going to be less actual use time every month/year
I can write much more, but there’s no point. Batteries are consumable parts and cost 100 to replace every 2-3 years if you want peak performance.
And if you are fine with 60% of the original capacity to begin with, why bother? The battery will reach that point after 5-6 years anyway, but at least you enjoyed 100-90-80% for quite a few years.
I agree, though to be fair, this mostly applies to people who use most of the battery's capacity throughout the day and still obsess over battery health. They indeed do use only a portion of the battery's capacity because they allow their schedules to be interrupted by charging a battery that has enough juice left and at that point you're just willingly cutting the capacity of your battery in half in practical terms. Those users are inconvenienced needlessly by their own making and that defeats the point of slowing down battery degradation.
With that said, choice is still a good thing and I guess it would be fairly easy for Apple to implement a toggle in Battery settings where you can choose that you max charge is always 80% instead of a 100%, done. That may mess with Optimized charging, but just pop up an alert saying using 80% as max charge disables Optimized charging and that's that, user's choice.