I think very few of them look for someone available before posting a wanted ad.
Searching through the wanted ads is a pain in the rectum because of all the ads with the all instruments option ticked so when you've filtered for metal bands looking for a 40+ year old bassist who can commit to weekly practice, half the ads that come up are actually looking for something completely different.
I'm sure if I was a 20 year old female accordion player available to go touring with a electro pop duo I'd do much better.