No problem. just a common courtesy. I usually don’t post something I’ve read in another thread written by another person unless I am personally claiming it, and willing to defend it as my own beliefs — and then I’d still ping the original poster in case they wanted to come and defend their own opinions.
But usually I don’t post other people’s thoughts, I let them decide where they want to do so. Once in a while I’ll put a LINK over to someone else’s thoughts, that way people can go make comments in the original thread.
But there are people here who talk about other posters all the time without pinging them. There doesn’t seem to be a hard-and-fast rule, but I always felt that was like talking about people behind their backs.