CB circuitry has had a tradition of keeping costs down by using stages for two purposes. In the case of the receive audio, the audio amplifier is also used as the modulator. In receive, one popular way to mute and unmute the audio is by adding a wire that provides a ground return for the the modulation/audio output transformer. It's opened during transmit and closed during receive. Typically FM commercial and amateur radios use seperate circuitry for both transmit and receive. FM carrier isn't modulated either by audio, the frequency is instead. Solid state switching is often done by rf diodes that a control voltage is applied to and direct the rf from the transmitter to the output connector and visa versa in receive and also use a transistor to mute the audio. Relays are also still in use especially at higher power levels. There's no current flow in the amplifer stages either when there is no drive, so the PA transistors are "hot" all the time and biased to cutoff. No need for power switching to the output stages. In this day and age, relays are still very common in commerical and amateur radios as well. All comes down to cost savings.
Only DIN connectors I ever seen have problems were those very cheap plastic snap in type that press fit into a hole. I only seen that in very cheap AM sets. Board mounted ones can also present a problem if the connector isn't supported well, but other connectors are mounted that way too and shouldn't pose a problem unless you really abuse the connector vs. a chassis mounted connector. There is a distinct possibility that if a mic is streched to the limit, the tension might..and DIN connectors usually grasp the pins pretty tightly as does the shell, pull off. If you're stretching the mike that hard, sooner or later you're going to have problems with any connector.
