You can recover from that far nose up, but the recovery will be bigger and need more time and potentially more altitude, commodities you may not have just after take off. Granted, the margins between stalling attitude and commanded attitude may be similar for a FD command of 18o when heavy and 25o when light, but you don't need to be pushing the aircraft close to its performance capability when light, and you're increasing the chance of triggering TCAS, so why do it when 20o will give all the performance and more than you need?
Centaurus, I both agree and disagree (mildly) with you.
I agree that FDs are not infallible, and that they have led, along with FMCs and other automation, to a loss of basic SA and flying skills. I only disagree that they're hard to look through - as long as the rest of the instrument scan is maintained to corroborate and anticipate the FD commands, then I think it's not a difficult thing to do. Shame so many blindly follow them, failing in the rest of their scan.