It would be more accurate to say that Results are proportional to the amount of effort that you put into the act and leave it at that. I hardly feel that you re in a position to know the level of effort that I, or others, are putting into our workouts by simply looking. That is how many gyms make a chunk of money - they know that statistically there will be a certain percentage of people who join at the beginning of the year that won't continue past a certain point. They help you tone up so to speak, and that's it. Total disagreement here.
Machines provide resistance.
They will respond equally well to machines - with the notable exception of working less stabilizers during the lifts, which, BTW, doesn't affect growth as much as it affects control. You'll get mixed responses from this one. Growth, on the other hand, would be difficult to obtain with just cardio. Anything is possible. A protein poor diet mixed with weightlifting would probably yield poor results - your body would be more prone to catabolize muscle to effect repairs on the damaged muscles, which means that an increase in muscle is not a likely happening.