Is the "breaking TLS" rant referring to the mechanism for doing so or to the reason why the mechanism is being used (and/or who is using it)

This is a totally different class of software than what that post is ranting about. Charles is a local developer tool intended for temporary use when debugging. It only inspects TLS connections if 1) you enable that feature and 2) you add the domain being connected to the list to be inspected.

That being said, the mechanism is the same. Charles generates a root certificate that it uses to issue certificates for each domain in intercepts a TLS connection for and you need to install that root certificate in your OS such that your clients will trust that certificate. If you have a client that doesn’t use the Mac OS certificate store you may have to do some extra per client configuration.

I also despise “security” tools that intercept and inspect TLS traffic (such as ZAcaler for example), but I find a Charles to be very useful for what it does and the TLS inspection support is easy to use and really helpful/necessary in some cases.

You can do more, e.g., changing the status code

Dev tools is an "inspector" and limited in scope, like a butter knife, a real proxy tool is like a Swiss Army knife.

super useful when you have an application, i.e. not a browser, that is making api calls that you want to inspect.

I'm also using Reqable, for those interested check it out: https://reqable.com