You click the sound icon, then the slide opens up, then you can either slide it or click one of the two icons.
It’s probably quicker to change the volume from one to ten this way, but 99% of my use cases for changing volume is for one or two steps, for which the slider absolutely sucks.
It’s some of the worst design I’ve ever seen for volume control, and the old system is some of the best.
You press your finger on the sound icon, and just start sliding without waiting. It's one fluid gestural motion. Try it out. It takes the same effort as tapping a physical button but gives you more fine grained control. Yes, it's something new and different from the way you're used to, but give it a chance.
I'm aware I can do this. It still drives me nuts - and I have to agree with eksemplar when I think it is simply a serious step backwards in design and should be an option, not forced like the 2018 models.
Take a MacBook with the function keys, and one with the touchbar. Then adjust the brightness or volume on both at the same time and the hand that operates the touchbar gets “lost” so easily
The old way: click, you’re done. The new way: click, hold finger, slide, and you’re done.
Like I said, it’s faster to go from 1 to 10, but 99% of the times I use it, I’m just changing the volume by 1.
Hell, it’s easier for my brain to just click 10 times than to watch where the damn slider is too.