There is nothing anywhere which suggests the McCanns were in any way incapbable of performing all normal tasks because of alcohol.
I challenge you to provide quotes from these statements which suggests what you are claiming.
As for your reliance on a news article. Sorry, thats just silly but unfortunately to be expected.
Alcohol effects people in a variety of ways, as you will well know.
The drinking occurred on all the nights they visited the Tapas Bar.
Merely because you don't act tipsy, does not mean alcohol inhibits physiological and psychological responses. It is also of course acts as a depressant, but I'm sure you know that already.
As to the newspaper article it is still available.
On the night in question, they had barely started their drinking, before Madeleine 'disappeared'.
As to the most important issue here, well that's very simple isn't it.
The Mccanns and associates socializing came before childcare.
You may want to discount it, but that is irrelevant as far as I am concerned.