That's just a marketing/engineering choice. 19 revolutions seems excessive. I don't know what's common for steps-per-revolution but in home environments 1dB or 1/2dB steps should be enough resolution. In mixing & mastering you might want 0.1dB or 0.01dB resolution and that would need multiple revolutions.
Sometimes there is "acceleration" where quick movements make bigger adjustments than slow movements.
Inputs on an interface also need to cover a much wider range. You might be recording birds in a tree at a distance, or from a close-mic'd guitar amp or drum. And microphone sensitivity varies greatly with condenser mics typically being 20 or 30dB "hotter" than dynamic or ribbon mics.
I think its predominantly because The Motu has much smaller diameter knobs to be honest. its easier to have faster rotation like this . Also it goes in 1db steps and the flex in 0.5
"In mixing & mastering you might want 0.1dB or 0.01dB“. i personally dont cause when i want to hear 0,1 db ,,, No if i am honest i cant hear 0,1 db difference in Loudness Level as in „Turn the Volume 0,1db louder“ and doubt 99% of people would hear that.
I can hear 0,2-0,5 differences on the Eq easily though when working but its different cause Eq changes the way is sounds ….. ok lost track here
Returning to the Subject ,
I will make it the aim of my life to find an Encoder that regulates the Volume with the Feeling my beloved but gone Spl 2Control gave me.
Not directly 1 on 1 comparable cause its analog i know but i am talking about replicating the ergonomy of a thing like that in the Digital realm.