I thought the main problem was that it's debatable whether you can enforce it. So it harms users and distributions because they can't really rely on it.

But the liability would definitely be another issue. I think the law is different here in Europe, so the liability might already be included for my hobby tinkering per default and I don't need to worry.

And something else is: I'd include trademark... force people to choose a different name for their project if they take my code so there is no confusion and people can't upload versions with advertisements on some software store.