I'm going to offer a guess: say you're a wealthy person (whatever that word means to you) and you want a social filter to keep you from interacting with people who have less wealth. One way to do that is to buy luxury goods and only entertain conversations, dates, etc with people who do. most people would say that's inherently shallow, but say you were super rich, think of how hard it would be to find people to go on trips or activities with. How many times are you going to be met with "oh I can't afford it/can't get the time off work/etc" ? even being polite, that causes friction between friendships. The watch alone isn't going to do it, but taken with the bigger picture, it's at least a hint that you are of some minimum economic status and I imagine some people find that useful.

Interesting; I'd expect you to meet more of those people in those circles actually. Perhaps it's generational?