EXCELLENT question.
Myself, personally, do.not tip them, unless they do something above and beyond their job description. Getting my bag from the sidewalk to the ship is quite literally their job description
Just for the sake of a funny story, I can take it one step further.
The wife and I have a friend who inherited diamond plus status from her second husband. She went on one cruise and then got a divorce. (Another funny story for another day.)
She is now a 14 point diamond plus who shares her ex-husband’s status with her new husband and he has never been on a cruise but will be diamond plus on his first cruise with us in February
Herein lies one of the problems with the structure of the status sharing within the program