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.
I enjoyed James Somers account (HT Liron Shapira) of how Webster’s dictionary used to be much more beautiful than dictionaries today, for instance:
My guess is that dictionaries became ‘official’ and so are written in an official style. And that official style is contrary to color and poetry, because these things are in some way personal, showing glints of a specific idiosyncratic soul. And part of the point of officialness is that the entity having it is expansively clean and impersonal, involving specific people only insofar as they can be homogenized and branded and made fungible. You’re not supposed to look them in the eye.
I wonder if this is related to dictionaries being commonly treated as authoritatively defining words rather than documenting a group of people’s efforts to feel around for their meanings. Somers also says:
I got curious about the author of this dictionary, Noah Webster, and learned about his 1783 Blue backed speller (or formally, ‘A Grammatical Institute of the English Language’, speller section), which taught children to read and spell. It was the most popular American book at one point, according to Wikipedia, which also makes it sound like Webster might have had a substantial part in making American English different from English English:
Here is a version of Webster’s dictionary online, and Somers describes how to add it to your computer (which surprisingly worked for me in spite of his article being from 2014.)