No matter how you trust your software, some malware may want to activate it, especially at a high-value target like Zuckerberg (or Bezos, or Nadella, etc).
Alas, microphones are not as easy to deactivate.
If someone can access my camera and spy my unkept beard, why won't they also be able to access my keyboard and spy my main email account password?
Lots of young girls were being lured into installing malware and had their bedrooms recorded.
¹(Edit) You can't make this stuff up: https://support.apple.com/en-us/HT211148
That’s why eg. all Purism products with them have hardware kill switches (to physically disconnect them).
Easier on desktops that don't have a built-in mic.
I use a mic with a hardware power switch.