User blog comment:Real Godisme/Chapter 479/@comment-25111584-20160328140249/@comment-7418318-20160328163229

You're talking with outside perspective and hind-sight here.

Did Lucy know that Natsu was holding back to protect her, Mavis or the guild hall? For all she knew Natsu could still have been weakened by his almost dying or from his fight against Zeref.

Sure Lucy had no way of knowing Happy would stop Jacob from re-casting his spell but with 113 mages being freed in addition to Natsu, there was at least some chance that someone of those 114 people would be able to stop Jacob.

If she hadn't done it, there was practically zero chance of winning and absolutely zero chance of winning without anyone being killed.

Even if Lucy knew that Natsu was holding back and trusted that he could take out Jacob if she runs of, that victory would have meant the death of at least some people caught by Jacob.

On that matter, I'm not so sure Natsu would have been able to handle Jacob even without holding back. If you can't hit the enemy, it doesn't matter how much power you put into each attack. And I doubt a guy like Jacob could be beaten by omni-directional attacks. Sure they might hit, but would an attack that spreads the power over a wide area still have enough point-damage to take down Jacob? Maybe, but I doubt it.