Given that many users here aren't native English speakers/writers, the tone that might seem obvious to you & I, might actually be completely inadvertent.
Using the :D emoji at the end is a way for the author to reiterate the "No offense but..." type statement. The problem is, if they use that, it's likely they recognize their comment can be taken the wrong way and should have just rephrased it instead of taking the easy way out with the :D.
