On: Gmail Now Tells You Who You Want To Email

I don't understand. If I hit reply, then I reply to the person who sent. If I hit reply-all, then I reply to everyone who got the email (barring bcc, of course).

This is unaffected by To or Cc was used.

Did I miss something?

That sounds right for Gmail. Maybe his experience is with another email client.

Either that has not been my experience, or I've lost my mind. Both are possible.