This is hardly unique to Singapore. In Britain, it's the networking at Eton that forms the basis for political and administrative appointments.
In America, it's friends who formed strong bonds while they were in Stanford or Harvard who team up to start companies. When they go public, they look for their own kind to fill the boardroom.
It is human nature to look for someone you know and trust when it comes to choosing a member to join your team. In the world of sports, you look for someone who compliments your style of play. In politics, you're looking for those who share your vision of how the country should be run.
likewise google is cronyism. meritocracy is an illusion!