Where the danger lies for me is if I'm reading a thread about a book I've already read, and a recent post from someone who's further along could say, "This reminds me of what happened in the novel that came out last month..." and then they proceed to give away plot points about something recent in a thread that's actually about something else. THAT is what I object to. It's inconsiderate.
What's inconsiderate is thinking that the rest of the posters must stop and consider you
first before posting. What makes you think people like me want to post here if we have to walk on eggshells to avoid offending you
It's not walking on eggshells to use a spoiler code, it's called being polite.