[lisper]

The useful load of a PA-32 is about 1500 lbs, so yes, you can put 7 180-lb adults in it and still have a little margin. What you cannot do is carry 7 adults plus their bags plus full fuel. Even without bags, you could not go very far with a full plane.

Some planes have more margin: the Cessna 182 for example is a four-seater and can carry full fuel plus 800 lbs, so you really can load it up with four people plus bags and still go somewhere.

But all planes will be close to their operating limits when fully loaded. Even a jetliner will typically be very close to its operating limits on takeoff and pilots have to pay very close attention to this. If you think about it, this has to be the case. If it weren't, the plane would have been over-designed and much more expensive than it has to be, and so it would lose to the competition.