Well, you choose a username in a specific context, even if it's public.
For example, you may agree to have your linkedIn profile name next to your HN username... maybe. But I'm not sure that you would agree to have your LinkedIn profile name next to your Tinder username.
And you sure don't want that to happen without your agreement and even without you knowing about it (but learning about it from a colleague for example).
That's why GDPR has some right to deletion or modification. And why some days, Europe may go after data brocker
(as a side note: not sure why my comments were downvoted. I didn't say that I would go after anybody - and surely not HN - I only said that uncontrolled use of any data without any anonymization and without consent might be the source of problems with regard to legislation decided BECAUSE too many shady business abused of it. You may not like it but then... well... downvote the abusers)
For example, you may agree to have your linkedIn profile name next to your HN username... maybe. But I'm not sure that you would agree to have your LinkedIn profile name next to your Tinder username.
And you sure don't want that to happen without your agreement and even without you knowing about it (but learning about it from a colleague for example).
That's why GDPR has some right to deletion or modification. And why some days, Europe may go after data brocker
(as a side note: not sure why my comments were downvoted. I didn't say that I would go after anybody - and surely not HN - I only said that uncontrolled use of any data without any anonymization and without consent might be the source of problems with regard to legislation decided BECAUSE too many shady business abused of it. You may not like it but then... well... downvote the abusers)