Also, why is it opt-out and not opt-in?
A lot of services, newsletters, promo, telemetry, are by default opt-out. When you install some chat app, it also syncs some data (e.g. contacts maybe?) and then you can go in the settings and opt-out for that sync..
Let's be real here, the difference between opt out and in is probably several orders of magnitude worth of data. It's like, would you rather have a Megabyte of telemetry to analyze or a Gigabyte?
Since a few weeks, our hackerspace - which used to publish all door unlocks on IRC with the nickname of the person unlocking it, by default - requires opt-in for nicknames to be published.
People recognize that this is an important social function of the space, because it ties together the IRC channel and the physical space, and thus the vast majority(!) of members have explicitly opted in.
This whole narrative that "if you make it opt-in, not enough people would ever do it" always conveniently leaves out that that's only true for things where people don't want to opt in, ie. usually things that benefit the service but not the users.