I think the diet part of the info is required along with body stats. Higher levels of body fat increase the likelihood of estrogenic side effects, because there are more receptors present. I believe that's why people ask for diet and body info - because overweight people are trying to use the AAS to cut from 20+ BF down to 9% and might get difficult to deal with sides like gyno.
The skinny bugger who doesn't know how much he's really eating, might not maximize their initial cycle gains. I'm under the impression, from what I've read, that the first cycle can produce great results if all your ducks are in a row, and that these results might not be as easily reproduced in subsequent cycles.
Granted this is all my personal opinion, based on things I've read, and I'm sure people will correct me if I'm wrong.

