The issue is not specifically about battery life, but about the ability of the battery to provide a stable voltage under load. The voltage of the cells sags mor

The issue is not specifically about battery life, but about the ability of the battery to provide a stable voltage under load. The voltage of the cells sags more under high current draw as the battery ages; reducing the current draw by throttling the maximum SoC frequency seems to be intended to avoid the problem where the voltage dips to a level that causes the SoC to shut down suddenly.