I don't use FF portable for online browsing.

Remember, lots of different users of differing technical abilities use portable software, and most of them won't manually code a batch file to clean things up. Additionally, crash logs contain personal data, so while you may not care, I think most users would be uncomfortable with some of their personal data left behind on some random PC. Just because the handful of extensions you use don't break doesn't mean that lots of others do, particularly when a new version of Firefox is released and extension X isn't listed as compatible in its manifest but is actually compatible so lets your install of Firefox know. And Mozilla sends folks our way when they want a portable version of Firefox to distribute on USB drives. We negotiated a license to use the Firefox trademarks. If you request a portable version of Firefox, ours is as official as it gets. They don't document or support it as a 'portable' implementation as it is not designed to be used as such. Well, if that's not enough for you, Mozilla calls the -profile switch a way to point to a specific profile.

Firefox portable