[aidenn0]

Very inexpensive digital circuits can perform calculations on their inputs with much higher precision than any analog calculator ever built. Weight, volume, power, or dollars, pick your cost.

Yes, you are limited by your measurement, but you are so limited when operating entirely within the analog domain as well. Therefore it makes sense to make your measurements as accurate as possible, quantize once, and be done with it. Keeping it in the analog domain merely allows more points for noise to enter the picture.