For the obese and fat, definitely. For those who are lean - Men 10-14% body fat or women around 20% body fat, it's a completely different story. But...
You don't have to do them unbroken - you are allowed to rest. Other options include ring rows (if available) or using bands to assist your pull ups. ...
so.... your first crossfit WOD shouldn't be a hero wod... seriously. Theses are 30+ minute painstorms designed to test you, not make you more fit. so...