What I think happened here is an Anthropic team with very little security expertise were working on finding bugs for marketing reasons and when they prompted to make POC exploits of those bugs they didn't have much success because they didn't really know what to ask for. They then proceeded to very finely tune their next model to eagerly exploit vulnerabilities making the models much more powerful for the "I don't know what I'm doing" user which they're now trying really hard to convince everyone is a game changer. </speculation>
The reason many of us are skeptical is we've used the current models to do things and they've worked.
An analogy might be if they tuned their model to eagerly instruct somebody how to make improvised weapons, now somebody is asking about how to deal with a rival at work and their model gives instructions on building a bomb from hardware store parts. Then go on a marketing spree telling everybody how dangerous it is. This example might highlight how insincere the marketing is. At any point you could have tuned the model to exploit for inexperienced people, now that you've done it does not mark a grand new capability. People who knew what they were doing could already do this with models.