Why do most solid-state transmitters reduce output power as SWR increases beyond a certain level?

Solid-state transmitters use sensitive RF output amplifier transistors that can easily be damaged by operating beyond their voltage or current limits. When the Standing Wave Ratio (SWR) is high, it means that a significant amount of power is reflecting back from the antenna to the transmitter. This reflected power combines with the forward power to create high voltage spikes and excessive heat that can quickly destroy these final amplifier transistors. To prevent this catastrophic failure, most modern radios have built-in automatic protection circuits, often called "foldback" circuits. When these circuits detect an abnormally high SWR, they automatically reduce the transmitter's output power to a safe level. Distractors like complying with FCC rules or power supply limits are incorrect because this power reduction is strictly an internal hardware protection mechanism, not a regulatory or power supply limitation.