The steps doesn't say you are capable of anything when drunk.
Step 1 asks the question are you powerless over alcohol. It means are you powerless over alcohol when you start drinking. Does it get out of control? Do you have difficulty stopping after 1 drink? Does alcohol control and dictate what you do in life? Does alcohol dictate what you don't do in life?
You need to take an honest look at your situation.
It also needs to you to consider whether your life has become unmanageable due to drinking. It may not be now, but if you continue drinking what happens?
Do you recognise that it is a progressive condition if you keep drinking?
In summary, it is about creating a self belief that you need to stop to fuel the massive commitment required. This commitment will likely be challenged by your subconscious later when you try and talk yourself into I am ok and a few drinks won't hurt.