I did not say it's justification for throwing away old equipment, but at some point, the high cost of replacing a battery (high because it requires a 'repair')

I did not say it's justification for throwing away old equipment, but at some point, the high cost of replacing a battery (high because it requires a 'repair') offers less value than buying a newer model. This is especially the case with, say, Apple laptops where the official battery replacement means the entire top-case and keyboard has to be replaced. A good way to keep these devices in use would be with an external battery, and one built into the power adapter would be very convenient. Just an hour of power would be enough to move around to meetings without multiple reboots.