Musescore is free and as @beet mentioned, Groove scribe is also handy to quickly write down some basic stuff & stickings. Then just use the snipping tool and voilaMaybe it's because the online forum doesn't offer a tool to readily insert a music staff into a post, add notes to that staff, and markup the notation with stickings and accents. I don't consider taking a screenshot of a Sibelius render, saving it to a file, and dragging that file into a forum post, as being a tool readily available. Plus I don't have Sibelius or any comparable notation app.
The other thing is, and I've mentioned this above already, tablature doesn't need to be seen as a replacement for formal notation. It should be seen as a supplemental tool. I find it particularly helpful in recognizing particular stickings like paradiddles, repeating and/or alternating.