I'd argue that the most probable reason is that the streamer doesn't want to pay for a second set of streaming rights to the other editions. I can imagine a situation where people complain about getting the director's cut because it wasn't what they remembered if the streaming service chose to show the director's cut rather than the version shown in theaters.

I like the commentary tracks on DVDs. A drawback of having DVDs be available not long after the movie leaves the theaters or even while the movie is still in the theaters, as was the case with "Tàr", is that those features are not available or are less available.