I don't see why people are surprised by this or why people are calling it a scam. Netlify and others are extremely transparent about the fact that there are no limits. I completely understand not liking it and can see why the lack of limits would make it a bad option for plenty of people, but I don't see how it can possibly be called a scam.
Upon review, it does not look like this is the case. I have several very low traffic projects on which would have never been anywhere close to the free limit. However, if I get involved in a random spam attack, it seems I could be on the hook for several thousand dollars.
This is incredibly dangerous. Netlify is often used as a beginner friendly free tier for static hosting. Not as something that is cheap, but as something that is free. This is just an overall dangerous position to put people in.