Analogue in general sense points to something continuous, not necessarily voltage. But even if you think of metered timing (that's what it usually ends up to be) there isn't anything analogue too, it's all happening in the digital domain. Just the pots, faders, wheels and things like that need AD. Even here there are alternatives with digital encoders - and before you ask, there aren't just incremental encoders, there are such encoding absolute values too, even if these are preferably used in industrial applications.
Finally for organs one does not need velocity at all... That's indeed not the #1 choice to make velocity accuracy a topic.
, I designed the first marketed guitar synthesizer (Digitone ORS GM 201). It used a (patented) digital "period-meter" to encode and memorize the period of (analog) guitar signals... 
