They facilitated (enabled?) it, would be more succinct I feel.
I mean, look at the details... Early that same day she was abducted...
Over breakfast Madeleine asked: "Why didn't you come when [her brother] and I cried last night?" After the disappearance, her parents wondered whether this meant someone had entered the children's bedroom. Her mother also noticed a large brown stain on Madeleine's pyjama top.
[45]
So already most *normal* parents would be asking what she meant by this and almost universally I think most parents would be asking where the stain on her top came from which wasn't there when they put her to bed?
But not the McCanns, They wanted their last night at the Tapas bar and nothing was gonna stand in the way of that, Not even the safety of their 3 young children.
And later still while actually abandoning their responsibilities as parents for yet another time by going to the Tapas bar anyway....
Madeleine's father carried out the first check on 5A at around 21:05. The children were asleep and all was well, except that he recalled having left the children's bedroom door slightly ajar, and now it stood almost wide open. He pulled it nearly closed again before returning to the restaurant.
[48]
Now OK sure, I will admit here, it is easily possible that it could have been one of the kids woke up for a moment, opened the door a bit, wandered around and then went back to bed.
BUT... considering the context of what had happened that morning, surely... SURELY this would be the warning sign that would make the father stay at the apartment?
Nope.. The McCann's need their Tapas party and to hell with any sense of responsibility or guardianship of these 3 young children, so he just pulled the door almost closed again and went back to his fun.
There really is no part of the story that elicits sympathy for these people. Their attitude and their actions are utterly reprehensible.