Though there isn’t a button for it when editing your bio, you can insert the old Chief Delphi userbars with markdown. For those unfamiliar with markdown, the syntax for adding an image looks like this:
![alt text](imgur link to userbar)
You can check my bio for an example of their usage. I’m hoping this functionality will help appease some people who want the old kind of signatures back. The imgur links can be found by searching [year of game] userbars on CD and looking for the imgur link.