"That person who made a racist joke on Discord when they were 13 years old? That should be able to ruin them when they're 30!"

Or society could move on and accept that people progress. Also I am not aware of any instances where 30 year olds were punished for a racist joke they made with 13.

The only instance I remotely know, is of a german politician, who made a deeply racist and neonazi pamphlet when he was 17 - and the result was some public outcry but nothing else.

Still privacy is important, simply because those who do surveillance are not trustworthy either.