Why transistor action is lost if base width tends to zero?

Transistor action relies on the recombination and transport of charge carriers across the base region. If the base width tends to zero, the movement of carriers becomes too rapid, leading to insufficient time for recombination to occur, which is essential for the transistor's amplification properties. Consequently, the device behaves more like a diode, losing its ability to control current effectively, and thus, transistor action is lost.