Welcome to the idea of an "implicit warranty"
This takes it to ridiculous extremes, but it is a valid legal concept.
If I sell you something, I also (like it or not) sold you an implicit warranty that it was good for doing whatever I said it would do. If it isn't, and you suffer harm for that misrepresentation, I am liable.
In this case it is stupid. Eating McDonalds every so often won't kill you in much less than the usual lifespan. I have as little sympathy for people complaining how unhealthy eating McDonalds is all of the time than I would for someone who complained that eating only fruit lead to vitamin deficiencies, time to sue the fruit vendor!
But in general I think the basic idea of an implicit warranty is a good meld between common expectations and reasonable ethical behaviour. Which is why I don't like it that Microsoft etc deliberately avoid actually selling you anything so that there is nothing implicitly warrantied for them to be liable for...
Cheers,
Ben
