Illustrator lets me set up keyboard shortcuts to 0/10/20/30/40/50/60/70/80/90/100% opacity and this is how I assign the vast majority of my opacity levels. Effectively I'm "losing" a lot more steps than just the difference between 100 and 255.
I'm also usually using some kind of blur on my shading, possibly filling them with a gradient that has different opacity levels on its stops, so there's a lot of subtler opacity happening in my work. Sometimes there's an additional modifier created by changing the opacity level of a group of translucent shapes, or an entire layer. Or a complex appearance stack of multiple fills and strokes applied to single paths, each of which has their own opacity level (and mode!) that's modified by the path's overall opacity. But in terms of my interaction with the whole system it's largely just eleven levels spread out across 0%-100%.
More precision would be nice now and then I suppose, I wouldn't complain if it existed, but in practice it's something I rarely need. Bjango does a bunch of super-fiddly UI work so maybe they need it more, I dunno.