I accept the possibilities of additional, powerful functions now appearing; but surely the real accuracy comes from the programme itself?
For example, if you want two lines to join, or shading reach an edge, or a circle have a finely-set diameter; the software can do that to pixel precision (even finer perhaps, arithmetically) greater than even the most experienced operator can do by sliding the cursor manually - as you would want if your aim is to create a file to control CNC precision-machining operations.
I'd have thought more to the point is comfort and particularly, avoiding joint troubles. Unlike word-processors, spreadsheets, databases and programming, which are perhaps the most commonly-used serious applications for computers, CAD demands considerable mouse-work.
When at work, I, along with others, suffered from various aches and pains due to using a conventional mouse, even though my own work was primarily keyboard-based. The company supplied us with what upright controllers looking superficially like joy-sticks. The ones we used were called "Penguins" by trade-names, an effect heightened by their mischievous aesthetics! They were made in different sizes, so we could select the personally best. Their point is that you hold them in a more natural position than a "mouse" mouse forces.
The one I have here at home is similar, though it does not have a scroll-wheel, occasionally a disadvantage though not so much in TC.
If you prefer a conventional "mouse"-shaped mouse, it is worth trying different ones if possible. One of my work colleagues provided his own, as he has small hands. It was smaller and more steeply dome-shaped, shaped as a stylised model of a VW "Beetle". It was actually intended for children but he found it suited his hand better than the conventional device.
I have been having shoulder trouble exacerbated by too much computer-using, and for the time being have become somewhat ambidextrous, using the mouse/joystick-shaped thing with my left rather than right hand.
So perhaps absolute accuracy in the device is not as important as being able to use it with as little joint and muscle strain as possible. Let the precision settings, inspector-bar entries and tool-bar functions, look after the numbers!