I think I’m most cases people just want privacy. A lot of our lives are broadcast on social media, even here. Keeping something to yourself is nice these days.
I also think those that are saying they don’t want to be bothered by people trying to buy their pins are lying to themselves. Is it such a hassle getting an email every few weeks (and I’m sure it doesn’t happen that often) from someone to buy a pin from you? Give me a break.