Iron Butterfly, Jeff Beck Group, and the Moody Blues: what they have in common

I am reading another book on Woodstock, this one called Back to the Garden by Pete Fornatale.  Comments and vignets from people who were there: artists, organizers, and attendees.  So what do Iron Butterfly, the Jeff Beck Group, and the Moody Blues have in common?  All were on the event posters and in the media ads - but did not perform.  Moodies were invited but they were not touring, it was too much trouble to go.  As for Beck, the author says the band was splintering at the end of their summer 1969 tour.  As for IB, in the book, festival stage manager and Fillmore East vet John Morris tells this tale.  After being invited, IB sent a telegram to event managers stating the bands' demands to be met if Iron Butterfly were to perform at Woodstock: "from LaGuardia, a helicopter will take us direct to event; we will perform immeidately, then be flown back out."  As legend has it  - Morris' (or Lang's) reply telegram to Iron Butterfly went something like this:

For reasons I can't go into
Until you are here
Clarifying your situation
Knowing you are having problems
You will have to find
Other transportation
Unless you plan not to come