I agree. When I was saying it wasn't a cultural thing, I meant that I don't think being rude and hateful is a large part of Dominican culture. The culture of the poster is definitely a factor.
Being an American, I can say that culture differs greatly depending on where you are in the country. I'm from Texas, and the Northeastern culture for instance can seem odd to me. There are things that would be rude in Texas. For instance, eye contact is an example. Where I'm from, it is rude not to salute anyone that you make eye contact with. Also when waiting with strangers, you're supposed to engage if a conversation starts or start one yourself. When I went to Punta Cana, it was mix of people from everywhere. Now that I've been going to Sosua/Cabarete, I encounter a lot of tourists from up there, and I occasionally have to remind myself that some things aren't intentional.
One thing that drives me crazy as a Texan is the lack of "Thank you" in the DR though. In private, I would have been slapped in the head as a kid if I were handed something and didn't say thank you. In public, I would have gotten the ominous question, What do you say?