I don't normally get into this type of conversation, and I don't mean to pile-on either, but I think that the target of the dismissiveness is a distinction worth pointing out. The post that you originally replied to was dismissive about some mindfulness techniques. You made it more personal, accusing the poster of being dismissive. This is directed at a person. It's less abstract, and their more likely to cause offence or annoyance.

My general rule is that I try to have thicker skin when it comes to assaults on ideas, and be careful not to offend persons.