I don't think "don't chime in if you don't actually know, or just ask instead of make a baseless assertion", is "insulting". If anything it's just bluntly pushing for better nettiquette, and coming out swinging in the manner your post did does no favors.

Just take time before posting to ask yourself "is this asking a question, or am I making an assertion I'll excuse as being a question later instead of just asking?" Your post was very much the latter. I don't think you intended it, but it's a byproduct of conditioning short-length social media engagement has kind of created in many of us overtime. It's healthy to undo that.