Why is the collector feedback bias popular in electret-mic preamp circuits?

Most of the hobbyist circuits you find by googling are crap originating from dubious tinkering and then copied from each other. The bias level of this circuit is not very predictable from BJT to BJT (meaning it may clip at high level one way or the other depending on the capsule sensitivity and actual sound pressure level) and the distortion is relatively bad (due to the lack of negative feedback or emitter degeneration).

The JFET (internal to the capsule) is much less of a problem because the signal levels are in the mV at the drain so the signal current is a very small percentage of the bias.

Try looking for commercial pre-amplifier circuits or (generally much more expensive, but also good performance) application notes from companies trying to sell chips. For example this circuit from Maxim. TI has some designs as well.

This circuit guarantees Vce will be larger than Vbe.

Over the VDD range of 3v to 9v.

No matter what the transistor BETA.

No matter what is the temperature.

Only a broken transistor, or a very leaky transistor, can flummox this negative-feedback-DC behavior.

Note the gain is effectively the Rfb/Rsource, unless the Rfb is center-tapped and a large capacitor used to AC_bypass the centertap.