Yes - that was a bit OTT. Mind you, wasn’t that the tour with full orchestra and choir? Not quite so excessive if you’re talking about 100+ players. Knowing first hand how commercial airlines can treat musicians and their instruments, I don’t blame them for making their own arrangements.
A big part of the problem in the 70s was primitive technology. Synths were not generally programmable, most could only produce one note at a time - hence the huge banks of keyboards that became the hallmark of prog excess, though it was actually born of necessity. In those pre-MIDI days, keeping them in tune and in sync was a nightmare, if it could be done at all. If parts became complicated, extra musicians had to be drafted in because one player simply couldn’t manage to play even the simplest chord if each note had to be played on a separate keyboard. A case in point, from 1979:
Shame about the shite vision mix - it was being filmed for TV, but the plans were shelved and the master tapes wiped for reuse. All that survived was a rough vision mix done on the fly on the night. Half the time it’s spotlighting the wrong player. Still, at least the sound is pretty good.
These days, of course, all that could be managed by a single player with one or two MIDI controller keyboards and a laptop. With so much being synced and sequenced automatically, though, you lose a lot of the live feel, IMO.