I have seen guys out there reeking of booze but totally upright and able to fly very well indeed; terminal alcoholics running on booze far better than trying to cope without! You really think someone like that would consider calling in sick... for what? He's coping just fine, thank you very much!
I once had this very man 'on the carpet.' Of course mine was a very small carpet (acting Deputy Chief Pilot), I was ex-military but a former enlisted man not once an Officer and a Gentleman and I was taken to be just over-reacting to such facts as that, yes, he kept a bottle in his room.
I was told that was only 'to entertain guests.' I had to point out that I sometimes entertained guests too but that didn't entail keeping a bottle in my room! Well, nothing worked until the hammer had to come down, when the guy ended up having to go all the way down, no job, no licence, before he could work his way back up to living without booze. That is often how it is.
When you look at it in the light of experiences like that one it's much better to treat drinking as a disease (whether you choose to believe that or not) like any other that is treatable and often controllable. Otherwise you have your closet drinker putting people at risk until he's caught. It is much safer to get the problem out in the open, I think.
Big airlines are not really all that charitable towards their employees, are they? I think they take the approach they do, treating alcoholism as a disease, for very sound safety reasons.