This approach is usually less stable and cannot generate the low frequencies that a heterodyne oscillator can.
From the en.wikipedia.org
Regenerative Detectors work well for narrow-band signals, especially for CW and SSB which need a heterodyne oscillator or BFO.
From the en.wikipedia.org
Modern circuit designs often simplify this circuit and avoid the complexity of two heterodyne oscillators by having a single pitch oscillator, akin to the original theremin's volume circuit.