There's really no need to force this decision to go in either direction. Ever since I first heard of capacitive multitouch, going back to the timeframe before the first iPhone announcement, I've been waiting for someone to build 'stick-on' encoder knobs that the touchscreen controller can read.
These would simply take the form of a knob with a metal leaf or other polygonal electrode in its base, whose rotation could be sensed by code similar to that used to implement crappy 'virtual potentiometers' on existing touchscreens. The fixed part of the knob base would be epoxied or otherwise bonded directly to the screen surface, or perhaps held in place with some sort of frame.
Doesn't seem to have happened yet despite being an incredibly obvious (and inexpensive!) thing to do. Seems like the MIDI community would be all over something like this, even if no one else considered it worthwhile.
Being able to set the dial on the screen and just turn it is a really good-feeling workflow, though likely not for something as mission-critical as the article is describing.
>On-screen detection: Touch digitizer reports the onscreen location through a capacitive pattern (Studio only)
I envision using cam levered suction cups to hold on rotary and linear sliders that had touch screen sensitive rubber tips. One could go as far to 3d print arbitrary interaction devices that could get attached to the face of the touch screen. You can use the multitouch sensor w/o the screen but still be able to configure arbitrary devices to go on the front.
I even had a design for joystick. Lots of analog opportunities when you have something like a back illuminated camera or a touch controller that can sense areas. You could also serially transfer data from the device to the touch screen, either using physical touches or electrically simulated touches.
I'd be surprised if the concept weren't already patented, though, just because the idea of a generalized capacitive control surface seems fairly obvious, and the patent office doesn't really apply an "obviousness" test. What definitely surprises me is that, patented or not, I can't just go out and buy these sorts of controls.
We would then be able to receive that pattern and understand how the knob is rotated.
What’s the resolution of todays touchscreen?
But for simple things, if possible without affecting the other parts of the screen, it'd be amazing to have a broadly supported, low bandwidth standard.
This might be as simple as "Here's my encoded position * frequency of sampling", but for a general interface you'd want something adaptable.
What if there were two dials on the control? Two dials and three buttons? One dial, four buttons, and a joystick?
Check this: http://huyle.de/2019/02/12/accessing-capacitive-images/ As you see, the sensor elements are huge, 4×4mm each, i.e. there’re only 15×27 sensors for the complete touch screen. On top of that, there’s high amount of noise in the signal of each sensor.
The reasons why it works OK in practice, fingers have very predictable shape, also a lot of software involved on all levels of the stack. Touch screen firmware filters out sensor noise and generates touch points. Higher level GUI frameworks “snap“ touches to virtual buttons, some platforms go as far as making virtual keyboard buttons different sizes, depending on which virtual keys are expected to be clicked next, according to predictive input software i.e. dictionaries.
What you propose probably can be done, by using a finger-like object, but I don’t expect the resolution will be great. At least not in comparison with hardware turning knobs, even cheap ones can be make extremely precise. See this https://en.wikipedia.org/wiki/Rotary_encoder and https://en.wikipedia.org/wiki/Incremental_encoder for more info, both are used a lot in wide variety of applications. Old mice with a ball had 2 of them, the reason why ball mice sucked was not sensor precision, it was dirt accumulation, a minor issue for a knob.
 VR and AR Fundamentals: https://medium.com/@michaelnaimark/vr-ar-fundamentals-prolog...
 Other Senses (Touch, Smell, Taste, Mind): https://medium.com/@michaelnaimark/vr-ar-fundamentals-3-othe...
 Food Simulator: https://www.wired.com/2003/08/slideshow-wonders-aplenty-at-s... https://ars.electronica.art/center/en/food-simulator/ http://icat.vrsj.org/papers/2003/00876_00000.pdf
Hiroo Iwata is a brilliant mad scientist , and in a previous HN discussion about pie menus and haptic multitouch interfaces , I linked to his wonderful work on 3DOF Multitouch Haptic Interface with Movable Touchscreen.  
 Professor Hiroo IWATA: http://www.frontier.kyoto-u.ac.jp/te03/member/iwata/index.ht...
 HN discussion of pie menus and haptic multitouch interfaces: https://news.ycombinator.com/item?id=17105984
 3DOF Multitouch Haptic Interface with Movable Touchscreen: https://www.youtube.com/watch?v=YCZPmj7NtSQ
 3DOF Multitouch Haptic Interface with Movable Touchscreen: https://link.springer.com/chapter/10.1007/978-981-10-4157-0_...
>Shun Takanaka, Hiroaki Yano, Hiroo Iwata, Presented at AsiaHaptics2016. This paper reports on the development of a multitouch haptic interface equipped with a movable touchscreen. When the relative position of two of a user’s fingertips is fixed on a touchscreen, the fingers can be considered a hand-shaped rigid object. In such situations, a reaction force can be exerted on each finger using a three degrees of freedom (3DOF) haptic interface. In this study, a prototype 3DOF haptic interface system comprising a touchscreen, a 6-axis force sensor, an X-Y stage, and a capstan drive system was developed. The developed system estimates the input force from fingers using sensor data and each finger’s position. Further, the system generates reaction forces from virtual objects to the user’s fingertips by controlling the static frictional force between each of the user’s fingertips and the screen. The system enables users to perceive the shape of two-dimensional virtual objects displayed on the screen and translate/rotate them with their fingers. Moreover, users can deform elastic virtual objects, and feel their rigidity.
There are some other really bizarre examples of haptic interfaces in the AsiaHaptics2016 conference videos! (Not all safe for work, depending on your chosen profession, predilection for palpation, and assessment of sphincter tone.) 
 AsiaHaptics2016: https://www.youtube.com/channel/UC8qMmIgmWhnQBeABjGlzGbg/vid...