I've been a party to that same conversation more than a few times.... and on the receiving end a number of those times.
 
The last time it came, (+/- 25yrs ago) I was playing in a house band and had been in the band for 2.5 years.... the call came on a Monday evening....since we had just had this conversation with another band member and no one would "man up" at the meeting.  After I got "my" call, I contemplated the decision to quit or to beg as others had done. Tuesday after work, I stopped by the club, entered in my usual way (through the bathroom window) opened the door and removed all my gear from the stage and the sound rack.  I didn't call them  or inform them.... I figured that they would find out and have enough time to make a plan from Wed evening (normal rehearsal) to Friday at 9pm.  I figured they could dig up enough songs for the singer to cover the entire show by himself..... we had 3 singers originally, but one had already quit some time back.
 
the call was not unexpected since there had been the classic signs of a band in serious trouble for quite some time. More then the normal grumbling about other band members, one of the 3 singers and a second keyboard player as well quit out of the blue, people missing rehearsals, and then half the band wanting to fire the other guitar player then backing off when confronted when he asked "So.... what's this all about?"
 
Oh yeah, after I removed my gear, I left a sign that said....... I QUIT!!!  the one with that now classic little boy in a picture doing the deed on the words I quit.... I think they got the message.  They didn't call me about the "I quit" issue, so they must have been serious about that or relieved that they didn't have to confront me like they did with the other guitar player...... but they did get the sound guy to call about the missing rack gear.  I told him that I was borrowing "my" portion of the gear for a few days but they could buy my ownership share at any time for what I had in it.   He showed up the next day with cash in hand.
 
The band continued on for several more months before it went down in flames. They started rotating member in and out, fired or quit, more often than a McDonalds fry-man job. I got out before the real problems started. I remained friends with most of the band and several told me after the fact that they wished they had quit at about that same time because things got really bad there towards the end.
 
Once you start to see those signs, and we all know them now..... time to move on.
 
The good thing is that you can't get fired from here.

Signs you may be in a bad band...

1. Claiming you play anything "just like the record"
2. 80% of rehearsal time spent re-tuning, 10% arguing Zeppelin vs. Tull, and 10% trying to find the singer
3. Asking, "what do you mean, 'Rehearsal'?"
4. Any band member's girlfriend/boyfriend is the "Manager"
5. Every time you're about to start a song, one guy asks, "How does that go, again?"
6. The drummer drops his sticks and the band suddenly sounds better
7. The rhythm guitarist may only know five chords, but his hair is perfect
8. You're the only member of the band who actually shows up for a gig
9. Your bassist cancels at the last minute and then you catch him playing at another band's gig
10. The one and only reason to keep the singer is because he owns the PA
11. It costs more money to photocopy the set list than the band will earn at the gig
12. The band outnumbers the crowd
13. The club manager stops the gig early because it's time for Karaoke Night
14. The keyboardist plays a different song from the rest of the band and no one can tell
15. 4 musicians, playing in 6 different keys, at 128 different tempos, in 1 song
16. Every song features the same 10 minute guitar solo
17. Falling down gets the most positive audience reaction
18. The band returns for the second set and plays the first set again because they didn't think they'd make it that far
19. The drummer breaks a head, a cymbal, several sticks and a drum mic on the first song
20. The rhythm guitarist plays half of the night before realizing his guitar was unplugged the entire time

 
 
These are just some that come to mind. There are many more.

21.  One of the band members uses a DJ setup

22. The dancers on stage outnumber the band