One reason I can think of is the intersection of the English speaking populations of the world. India, Pakistan, Indonesia, Philipines, and Bangladesh constitute over 25% of the world population. And these are also some of the largest English-speaking nations. It seems to me that the only way to cater to their needs given that only a fraction of the population can speak fluently would be through reducing the number of redirections. This is to say that it would be surprising if the incentives of one of the largest dictionary manufacturers in the world were not affected by a customer base that large.