I'm sorry Daniel, but I do not agree with your point. Your Elite/Platinum privileges were awarded to YOU by Princess because of the status that YOU earned. In the Princess Platinum/Elite list of privileges, it does not state that you can choose to allow non-Elite/Platinum passengers to enjoy YOUR Platinum/Elite earned privileges.
And in your comparison, you are comparing apples to artichokes. If I booked a suite, I can allow any one I wish to enjoy my balcony. I have that privilege based on the fact that I paid for the suite.
If you are in Club Class, should you be able to bring in non-Club Class passengers to the dining room? If you fly Business Class and your companions are in coach, should you be allowed to bring them into the Business Class Lounge?
As far as separating from your non-Platinum/Elite companions at embarkation, what we have done in that situation is to get in the regular line with our companions. Not extend OUR earned privileges to those that have not earned or have a right to them.
Sorry, I had to speak my truth...