I don't think your posts are offensive per se. I don't think most people want to actually come off as being offensive in particular.
That being said, I am agreeing quite a bit with what @Pernicious has stated. It's hard to address groups of people. It's even harder to address
them in a format where context and subtext may not be readily understandable. Don't take this me chastizing you either, because were all
people and we all got our own things to work on. It's encouraging to see that you're seeing this effect in action and communicating your pitfalls.
When I was at university, I minored in Linguistics and Communications. Believe me, being precise with language and its underlying savvy is
something I've struggled with my entire life. Its difficult, especially when casually addressing large groups accustomed to a different tone or more
professional style of speaking. It's something I feel I never quite master, but I do try.
I hope you manage to work this out in your own time.