What an extremely confusing blog post! I don't understand why it seemingly presents profiles as a new feature? Firefox has had profiles for years. What the heck is new?
I had to click the other link https://support.mozilla.org/en-US/kb/profile-management to understand that this is all about simple UI improvements to make it easier to work with existing profiles.
The blog post is more than confusing, it is misleading. HN should link to the support page instead of the blog post.