It's a bit like adding extra lanes, to some degree, demand expands to meet capacity (But I mantain that in this case the net effect is possitive)
There would be less space to be congested by fewer vehicles, but in this context, less congestion also means fewer people experience the congestion directly (because it also works to disincentivize car usage), but those affected have it the same or worse.
I wouldn't take my car to a large city center if I can at all avoid it, which seems to be the common reaction. These people are "transparent" to the congestion—they don't add to it and (mostly) aren't affected by it.
There would be less space to be congested by fewer vehicles, but in this context, less congestion also means fewer people experience the congestion directly (because it also works to disincentivize car usage), but those affected have it the same or worse.
I wouldn't take my car to a large city center if I can at all avoid it, which seems to be the common reaction. These people are "transparent" to the congestion—they don't add to it and (mostly) aren't affected by it.