For example AD8429 billed as 'ultralow noise' has 45 nV/√Hz output noise. So 45 is the noise at G=1 (input noise is negligible at 1 nV/√Hz) which is quite bad (tons of precision amplifiers are <5).
Why have an output stage with that high noise when it seems 'easy' to make amplifiers with much less. Are they assuming I'm going to use it at high gains (I'm not, I want a high impedance differential buffer and inst amps with integrated resistors are a cost effective way to buy that)?
Am I missing something dumb?