I think the primary driver is higher peak performance. With OFDM on 4G and 5G you can have very wide bandwidths for a given tower, and small, but high QoS alloc

I think the primary driver is higher peak performance. With OFDM on 4G and 5G you can have very wide bandwidths for a given tower, and small, but high QoS allocations for voice, or high bandwidth for video streaming. With 3G you had similar flexibility, but the peak RF bandwidth was ~3.84 MHz compared to ~40 MHz of 4G). This is doubly so with 5G. The maximum allocation is potentially huge from a time and (RF) bandwidth point of view, but an HD video stream is still limited.