It certainly is, I have the option to

1) Block the camera and hope the microphone is on mute 2) Hope the camera isn't on and home the microphone isn't on 3) Not have the mac at all

Clearly 1 is better than 2.

Support for this kind of thing is entirely voluntary. You can short the mic pin to ground (or connect an external mic), and it will disable the onboard mic by default because that's what is expected, but there's nothing physically stopping the audio controller from reading from the onboard mic anyway.

It's a shame they don't have a USB-C one that looks like a compact USB-C YubiKey.

That's incredibly overpriced at $26.99 for what is essentially just a dummy input...

To be fair it’s a 5 pack

It seems to be something with a switch that disconnects one of the rings of a 4 pin. Easy enough, but $5 doesn’t seem awful.

Of course it doesn’t disconnect built in microphones, and with modern Apple phones getting rid of 3.5mm jacks it’s value is less.

At $5, most of the cost is almost certainly logistical.

From my understanding it's not just a dummy input and somehow adds noise because some computers won't pick up the input unless there's a signal.

This is just for external headsets.

Internal microphones are not attached by such a port.