Two contributing factors, I suspect. Most importantly software can only deal with whatever hits the digital side; physics and electronics being what they are t

Two contributing factors, I suspect. Most importantly software can only deal with whatever hits the digital side; physics and electronics being what they are there are lots of places to lose information on the analog side. If you filter out that range before you add gain you probably get way better SNR and don't have to rely on some ridiculously sampling and high resolution to not lose things. Second - they have been doing this a lot longer than sophisticated software pipelines have been available.