peekay
Found it thanks, (must read the book again....).
As you say..
This is not type specific I think... you will find the same or similar wording even for the 777, 787, etc.
(actually it's not on our 777 sub-para of the joint FCTM, but given it's seems to almost apply across the board that might be an editorial issue).
As for a reason: If pushed my gut feeling is that JT has it (thrust against weight) - at/just after take-off you've got a combination of highish AOA/body angle, and changing configuration towards clean all with high power. Maybe once you're clean and the AOA's and/or body angle has reduced or at times of lower power (e.g on approach) the effect is less pronounced and the margin is less critical so Boeing don't think the effect is worthy of further mention....perhaps.........