If privacy or security protections are opt-out, Facebook, et al. will try to use any leverage they can to push their users to opt out. There's real value in a platform that doesn't give Facebook, et al. that opportunity. There are also obvious downsides; it's a tradeoff that might not be right for you but definitely isn't one-sided.

> that's no reason to prevent them from being opt-out

I’m genuinely surprised Meta and e.g. Citrix haven’t launched their own app stores in the EU. Maybe GDPR disincentivises the worst shenanigans.