In Macbeth, what is the importance of what the porter says in Act II, Scene III?

In Act Two, Scene 3, Shakespeare offers the audience much needed comic relief by introducing the intoxicated Porter who makes several witty, yet significant remarks during the scene. The Porter pretends to be the gatekeeper of Hell while Macduff repeatedly knocks at the door. He comments that he was pretending to be the devil's porter so that he could let someone from every profession into hell. The Porter's comments are ironic as Shakespeare links Macbeth's castle in Inverness, the place where Duncan's brutal murder takes place, to Hell. The Porter then jokes with Macduff about the effects of alcohol by mentioning that it increases desire but simultaneously impedes sexual performance. The effects of alcohol also allude to Macbeth's confusion and lust for power. The Porter's comments about sexual performance also echo Lady Macbeth's taunts directed towards her husband.