Comment by andrewia

That's an inherent limitation of modern lithium batteries with a smartphone's constraints of density, size, packaging, charge current, and a bunch of other requirements. Replacing a battery every 18-24 months costs ~$75 (or 1 hour and $35 if you're comfortable with DIY), which is a reasonable maintenance cost considering smartphones cost $300-$1300. Many car owners don't sell/scrap their car until repairs exceed the value of the car, we should apply the same philosophy to smartphones.