I have been on 7 Carnival cruises since the restart, never paid full price, and never had an issue with receiving shareholder OBC. The only hiccup was not with Carnival, but a relative, Princess, and it is only because they (Princess) now want a form filled out with basically the same information that I put in email requests.
On your observation, it seems complainers make a lot more noise than satisfied customers, and can distort reality.