Have the underline appear in the Markdown shortcut

I am not a veteran in discord but I have been a few years ago, a few months ago I discovered that an underline could be placed and I asked myself, why does it not appear with the other shortcuts? Sincerely, for people who join discord, it is most likely that they do not know about this, so if there is any reason why it is not with the other shortcuts, I would like a comment with the reason, thanks for reading.