In the real world it's not that simple. I'd love to close down my WhatsApp account - the only Meta service I've ever used - but unfortunately my employer requires us all to be in a WhatsApp group. I don't really have a choice in the matter if I want to get paid.
X is another tough one. Many politicians and public services use it as their primary channel for announcements. I've been using Nitter as a workaround ever since Elon blocked reading feeds without an account, but I feel like I shouldn't need to.
It's worth noting that Meta famously created shadow profiles. Not using a site is not sufficient when your data is for sale or sitting in some unsecured manner, waiting to be stolen.
Who would trust them? Even if one paid to not be tracked, they will still be tracked and that info will generate revenue. Once it's found out, they will pay a pittance fine and continue to track whomever they like.
Source: That's literally how businesses work..outside...right now.
It’s not always as easy. E.g. some small business owners must either maintain a social media presence on popular platforms or lose a significant part of their profits.
Having all users protected by default sounds ideal to me.
It's really not that hard. Under GDPR you have a right to privacy, and companies can't demand you give it up as part of some kind of condition to gain access to their service.