Oz, mate .. that's the problem .. it IS an operator responsibility at the end of the day. Most try to do a reasonable job of it, some not so good, a few don't even bother .. including those who might just look at the runway length limits and ignore the climb bits and pieces.
The message you, Mutt, OS and I have to get across .. is that it is not reasonable to expect the pilot to do any sums from scratch during the taxi out to the holding point ....