In principle you could say each array element has its own transceiver. But the computational load goes up with the number of distinct beams, and tight enough be

In principle you could say each array element has its own transceiver. But the computational load goes up with the number of distinct beams, and tight enough beams to address each subscriber individually would anyway need an array orders of magnitude bigger than the actual satellite. So instead we have binning by solid angle and frequency, and also TDM and software-level addressing. Some of that must be what makes uplink data rate so much lower than downlink. Point is just that practical limits make things rather worse than what a subscriber might naïvely hope for.