While it is meant to be an alternative to Chrome's profile switching, it is more a workaround than a complete replacement. I need entirely different sets of extensions for personal, work, and school environments, something containers can't do.
Firefox's actual profile support is beyond terrible. To launch a separate instance, Firefox requires many more clicks than Chrome, all within a Windows-2000-style UI. Not to mention that there are weird glitches in their implementation.
Firefox is not usable for me until they actually spend time improving their multiple profile support.