There are benign use-cases for this technology, though. For example, any TV/Radio ads containing the phrases "Hey Siri", "OK Google", or "Alexa" definitely should contain an audio beacon so that your iPhone/Android/Amazon Echo knows that a TV or Radio ad is playing, and not a human legitimately asking for a command.

…cue someone playing that inaudible signal continuously to block all people nearby using their Siri or what have you.

That's a really bad way to solve that problem, it relies on other systems following a protocol that they have no reason to even know exists.

A much better way to solve it, which is already being done (to some degree of success) is to calibrate the phrase detection to the owner's unique voice.

Reminds me of this namshub: https://youtu.be/xuGDhZorlQ0?t=23

Complain about what? Are the marker noises hurting your ears more than the commercials themselves?

Complain about the surveillance, hidden in an app I installed without any thought of that surveillance.

The same as I would complain about someone peering in my window from outside my house or through a long lense, which also doesn't physically hurt me.