They create unwanted alterations to the message or idea we are trying to convey, and are also a security problem (background fetching of the URL and allows for hiding of the actual URL.
We cant turn the things off, and the supposed workaround of using the Undo shortcut is only good for the author and not any readers.
Also you need to stop auto correcting JIRA into Jira. Even spell checkers arent as insidious as that little bit of script that is constantly requiring me to Ctrl-Z a few times.
