The woman was deemed partially responsible for the burns, because she was, the real reason is that McDonalds knew that people burnt themselves before, but did nothing to inform to customers of the risks.
People know that stunts on social networks have been punished, but keep making them anyway.
Which is not exactly a smart move and doesn't limit anyone's free speech, I am still free to say the same things, just not in front of a WorldWide audience.
Social networks will report immediately any "not conforming" opinion to avoid being the next McDonalds, but on a global scale (billions in fines instead of the 640k dollars MD paid)
https://www.enjuris.com/blog/resources/mcdonalds-hot-coffee-...