You are confused. This is exactly what pinning defends against.
Chrome does not perform pin validation when the
certificate chain chains up to a private trust anchor.
A key result of this policy is that private trust
anchors can be used to proxy (or MITM) connections,
even to pinned sites.
Also we are talking about apps implementing certificate pinning. Not reading from the OS store etc., and therefore, I don't see Kazakhstan reverse engineering and patching executables.
The fact that Chrome ships with a broken implementation does not imply the concept is broken.
I don't really agree with that, but it's IMO more useful to acknowledge the confusion, than having an argument about whether Chrome really does pinning or even gets to de facto define pinning or not, since this isn't even about Chrome :)
But still, I would have much preferred if the GP would have started their comment with "yes, but" instead of "sorry, no". That would have made the distinction much clearer.