I mainly see this with FUNi titles. Basically they give stream sites/services streaming rights for the dubs for a while, then it expires. Sometimes they renew it after a while, other times not. (usually with newer titles they don't get renewed quickly) Since Netflix is dubbed only, those are gone outright. Other places like Hulu keep the first 4 or so dubbed episode but the rest it up subbed.
I imagine this is a tactic to provide stuff for a while but make sure you DVD/BD sales are still reliable, since the dub is essentially the product FUNi is making.
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