It’s not an intuitive or discoverable command.
So my question: once you discovered that you could do a swipe gesture, did you find yourself using it often?
The best fix for this for me (the sliding was still a pain) has been to customize the touchbar like this:
In keyboard settings:
1. Change "Touch Bar Shows" to "Expanded Control Strip"
2. Add the 3 button volume and the 2 button brightness controls.
This setup behaves the most like the functional keys for me and has been the best at alleviating frustrations.
I still hope Apple nukes the touch bar though, it's the worst aspect of the Macbook aside from the missing I/O ports.
I feel that if you do the press and slide, the interface shouldn’t change to a slider (that needs to fade away).
I guess there's a still tradeoff: this way you need to move your finger around, but you can immediately skip to exactly the level you want. With holding a button down you have to time it to get to the right spot instead.
Personally I like the slider better but that's just my opinion.
If that bugs you enough to bother with a workaround, you could try something like this using HammerSpoon: https://gist.github.com/spinscale/fd82f00da29447990f27f36b3f...
Edit for clarity: when you do this, your finger is not actually "on" the slider handle itself. The slider shows up in its usual place, which is offset from where your finger is. But the sliding still adjusts it.
It's a shame that this is not intuitive or discoverable. Its much more efficient but I had to have someone tell me about it.