They actually have at least 3 kinds of profile: 1. containers - As they say its somekind of sandbox, technically a profile 2. profiles that are accesible through about:proflies, which they had for years, and probably the one you are talking about... 3. New profiles that comes with a pop-up much like how chromium browsers shows it

The old UI was pretty difficult to use, and hard to discover unless you knew where to look though.