He was their best attacking force, yeah. That's expected given his ability, his team mates ability and how they're set up to get the best out of him - that's not a criticism of Cristiano but it's nothing to praise him for either, it would be like saying Zlatan can never have a poor tournament with Sweden because he's their best attacking force.
Like I said, I don't think he had a poor tournament, but being the most threatening player in a team set up to get the best of him him is expected, anything lower than that would be a complete disaster. I think it's fair to say he could have played better in a few of his games, but similarly anyone who says he's to blame for Portugal not going further is just wrong.