Not sure why you're being downvoted. The option to turn Facebook sounds off on desktop was not there for me when they rolled it out (it was for others). I stopped keeping a Facebook tab open.
> Not sure why you're being downvoted.
Is it really about "mind control"?
(I wouldn't downvote it (and can't anyway), but that might be why others did.)
I think it is. I would bet money that Facebook employs or consults at least one psychologist to help them design their app for maximum addiction. An example from a few weeks ago is how "trending" stories are handpicked by humans.
newspapers also handpick trending stories. Sometimes they even write articles!
Is A/B testing really so insidious?
If it confuses users who don't understand why it's different for their friends, it can be perceived as such.
If the purpose of the test is to subtly herd your users towards a result which is good for business but bad for the users, then yes.
It's unclear how much A/B testing has to do with this. If I use a mobile user agent (e.g. Nexus 6 via the Chrome Dev Tools) I get the option to enable or disable autoplay.