Complex sentence: Although it is regarded as one of the greatest courses in the world, Pine Valley has not played host to any major professional golf tournaments, mostly because there is not enough room on the course to accommodate tens of thousands of spectators.
Split into simpler sentences: Although it is regarded as one of the greatest courses in the world, Pine Valley has not played host to any major professional golf tournaments. This is because there is not enough room on the course to accommodate tens of thousands of spectators.