I call it jealousy, pure and simple. Nobody cares about some old codger down the Dog & Duck going through Mustang Sally who states that nobody can match their 'feel'. Sure bud!
dementia
/dɪˈmɛnʃə/
A chronic or persistent disorder of the mental processes caused by brain disease or injury and marked by memory disorders, personality changes, and impaired reasoning.
Before I book, I make sure everyone can do the gig.
Let's say the gig is booked two months in advance - those on shifts will have no idea what their hours are until the week of. Gig cancelled etc etc.