"Analog Theremins will have oscillator coils"
Now, if it was stated that "Inductive (LC)oscillators give better linearity" then there would possibly be some truth.. BUT to equate "coils" to "analogue" is just utter nonsense - I can get rid of coils and still produce an LC oscillator by using a gyrator circuit to effectively simulate an inductor by using a capacitor's transfer function... I wouldnt do this, because the circuit is (much) more expensive than an inductor - but it would be an entirely analogue circuit which did not have any inductors.
The term "RF" is bandied about - Sorry.. but when one talks about RF these days, one (as an engineer) does not think about a 250kHz sine wave! There is more RF radiated from the PC you are using than you will ever get from a well designed Theremin! - And even with a Theremin based on a 555 timer will only 'radiate' a triangle wave at say 250kHz.. The energy of the highest frequency components of this waveform are hardly 'RF' by any standards, and are at such high impedence as to be utterly trivial.
It is quite easy to construct an entirely analogue classic theremin, with sine reference and pitch oscillators, and not use a single inductor (coil).. The frequency -> capacitance ratio is almost identical to an LC oscillator, and there are techniques to make it identical (or even better) to a LC oscillator in terms of linearity.
So - When you see ignorant assertions that "analogue = coils" or that "antennas made from Latinum improve performance (LOL)" BEWARE! - Best case, the advertiser is talking rubbish to woo you and put you off a competitor who uses different circuit topology.. Worst case, the manufacturer doesn't understand the basics of electronics, and does not know the difference between digital and analogue!