When you spend an hour in the middle of the night to change baby's diaper, feeding it, letting it burp, calm him down to the point of near-sleep, letting him drink again, another burp and oooh he finally sleeps...and then you hear 'PHHRRRHHHRRRT' coming from his pants. And you know changing the diaper will wake him up again, at which point he wants to drink again, and another burp, and another lullaby, setting you up for another hour of baby wrestling. Just putting him in his bed won't work because the dirty diaper will wake hik up in 10 minutes.
And with my luck, when he is finally sleepy again, he will wet his diaper again, restarting the whole cycle again.