For your aside, I don't think it's true. Search engine makers are well aware that language usage is what it is, and not what the thesaurus or grammar book says

For your aside, I don't think it's true. Search engine makers are well aware that language usage is what it is, and not what the thesaurus or grammar book says it is. Unfortunately, using machine learning to work out synonyms means you're going to miss out on minority usages, such as specialized academic jargon, or communities with millions of speakers which have slang and conversational grammar unlike "standard" English.