[roryokane]

I agree that one shouldn’t discourage one’s coworkers from making such complaints.

I think the person you replied to was not necessarily horrified at the complaint to a fellow engineer. They were horrified that the complaint was made within earshot of a cafeteria server, who might envy the engineer for even having the chance to make that much money. I think the principle behind that horror is “it’s rude to avoidably inspire envy in others”.