Now it's becoming more widely accepted, because it's becoming almost essential. The world is changing. Professional schools are grinding out graduates by the thousands. In some fields there are too many experts. The market is glutted.
Competition is fierce.
Even established firms experience a painful feast or famine cycle, because it's difficult to complete one job while looking for another. Referrals used to be enough to build a profession practice. In the past, if you did a good job, people would come back, and they would send their friends. You can't coast. Consumers want more for less.