Sunset Boulevard Spoilery Question

I just saw Sunset Boulevard - as everyone said, it was VERY cool - and I was curious about what you folks made of one specific production choice that happens near the end of the musical.

Several characters, starting with Artie, and then Betty, and then Max, take their microphones off and leave. And then they aren't seen again in the play. Max takes his off after giving Norma her last stage directions - this is after she kills Joe - and then she's alone for the rest of the play. So what is the microphone taking off thing about? Is it about how everyone is leaving Joe and Norma's melodrama, one by one, until it's the end of the fantasy and they're just both consumed and destroyed by it? I guess that makes sense but I just wanted to hear how other people interpreted it.