Thumb, you sure about that? I've had a bunch of electronic schooling, years ago, and the way I was taught how tone controlls works is by shunting a certain amount (determined by the resistive setting of the pot) of the higher frequency to ground. that frequncy that is shunted or let through to ground is determined by the value of the cap.
In a typical setup, when you roll off the tone, you are cutting out the higher frequencies, not boosting the bass
I could pull out some books and layout formulas etc...I am paraphrasing sorta how it all works. but the jist is, capacitors are a vital link in selectivly manipulating frequencies.
Maybe emg has some SMT caps or something that does not look like a cap, or maybe electronics has just left this old guy in the dust.
I have an emg active tone controll setup (david Gilmour) there are little circuit boards attached to the back of the pots, I am sure there are caps there, even if in a microchip
You have me curious now, I wanna find out.