Because the longer it takes to set the tables up, depending on how many tables are being used, the more it costs. Can you imagin the time it takes to set 16 3 piece slate 9fts up for an event? The more days you take to set up the event, the more it costs.
Diamond can set up 16 9fts up in about 3 hours,with 2 workers, ready to play, before an entire 16 man crew can even think about packing in all the parts and pieces for 16 Predator 9fts, and at a fraction of the set up cost alone.
Why would anyone revert back to setting up multiple 3 piece slate 9ft table events anymore, instead of using Diamonds?
While that is one clear advantage of using Diamond tables in a temporary tournament venue, I doubt it was what Dartman meant.