"The implication is that the EFDSS had strict metronome settings in mind for each dance. Which seems a little rigid to me. "

True enough and :

"When our band plays at barn dances/ceilidhs, we certainly take the composition of the dancers (young, old, experienced, etc.) into consideration and set tempos accordingly"

IBut at the rehearsal stage when 4 or musicians get together a tempo needs to be established?

1234 or 1 2 3 4 or 1      2      3      4?

How is this done?

Or are all those drummer jokes wrong and cruel because the drummer knows and sets the tempo and keeps everybody together and on tempo?