In a stereo design, the variable resistance isn't the only element responsible for the accuracy between the 2 channels.
With custom 5% tolerance potentiometers, 0.1% resistors and 2% capacitors all selected and hand matched in each design,
I obtain +/-0.1db of difference between left and right channels at all settings with 1951 Mastering Equalizer, sometime less

Now the "feeling" of a switched gear is important in a Mastering context imo. (and that's why I choose 21 detents pots). Although I don't have anything against continuous controls when doing Mastering, (I use an Spl PQ 2050 which has continous pots) switched or detented controls also allows you to get faster results, especially if you use a lot of different gears in your setup.
Another thing is that I personally don't like my ear to be triggered all the time by the sound of "clic...clic clic". I don't know about other engineers here but I like to listen to the music and hear the change I make without anything else
in the middle. That's one of the reason I also use detented potentiometers in my designs instead of switches.