I will hazard a guess that people were using it to 'spin' content for SEO purposes, by automatically translating others' content to foreign languages and back a

I will hazard a guess that people were using it to 'spin' content for SEO purposes, by automatically translating others' content to foreign languages and back again. If so, I imagine the double resource drain of doing that and then Googlebot indexing all that useless content would be a compelling reason to turn it off.