If there was an option that was presented to users once the device got below 80% battery health to slow down the system to make daily batter life longer
This isn’t why they did it. Degraded Li-ion batteries cannot sustain their rated voltage at high currents due to increased internal resistance. Sufficiently undervolted CPUs/memory cells produce errors (specifically bit flips), which can rather quickly lead to memory corruption and a crash.
Reducing the CPU frequency (thereby reducing the peak current draw) is practically necessary in the face of a degraded battery. Various laptops were infamous for not doing this, because it resulted in a ~20-30 minute battery life, as the voltage drop became too great once the battery charge drops below 80-90%. Within the context of a smartphone, neglecting to use the remaining 80-90% would make it basically useless.
What Apple (and the rest of the smartphone industry, at this point) really needs to do is make their batteries replaceable.
This isn’t why they did it. Degraded Li-ion batteries cannot sustain their rated voltage at high currents due to increased internal resistance. Sufficiently undervolted CPUs/memory cells produce errors (specifically bit flips), which can rather quickly lead to memory corruption and a crash.
Reducing the CPU frequency (thereby reducing the peak current draw) is practically necessary in the face of a degraded battery. Various laptops were infamous for not doing this, because it resulted in a ~20-30 minute battery life, as the voltage drop became too great once the battery charge drops below 80-90%. Within the context of a smartphone, neglecting to use the remaining 80-90% would make it basically useless.
What Apple (and the rest of the smartphone industry, at this point) really needs to do is make their batteries replaceable.