In the Open RAN architecture the radio unit handles the radio-frequency and lower physical-layer functions, connected to a distributed unit over an open fronthaul interface. Splitting the architecture this way was intended to let operators buy elements from different suppliers, which only works if the elements are genuinely interoperable.
The radio unit is where the deployment economics concentrate. It is the element replicated across every site, it contains the power amplifier, and its energy consumption is a recurring operating cost across the network's life rather than a one-off capital number.
Which is why this IP is built around low power and high bandwidth together, with the digital front end integrated rather than bolted on. The amplifier efficiency argument and the radio unit architecture are the same argument.