And obviously this is already happening— in the Canadian election a few months ago, there was a big scandal where some pictures turned up of the prime minister wearing blackface at a holiday party he attended in 2001. And on top of that there was a pretty steady stream of candidates (some of whom were indeed booted from their parties) who were challenged over social media comments/posts made 5+ years earlier, especially on hot social topics where national sentiment has rapidly evolved in recent times.
Perhaps we will all just become inured to this, and rightfully be able to accept our leaders as human, judging them for who they are today and not past words and deeds. But is it possible to still retain the ability to fairly judge someone in the present while forgiving the past? Or will we lose the ability to discern the difference? The GOP's attitude toward president Trump does not give me hope on this.
And, although I assume I'm in various Usenet archives, my participation there was always from a work address and was pretty tame. (BBSs mostly were too although all that content is gone anyway AFAIK.)
I could definitely picture political parties and businesses being willing to pay $$$ for an internet presence dossier as part of their larger candidate vetting process.
For example, about Sabu etc: https://sites.google.com/site/avalonlogsefnet/
Oct 29 12:28:53 <Cambion> we have logs that date back to 1993 and identify pretty much everyone from nickname change to nickname change
Oct 29 12:28:59 <Cambion> phone numbers, everything
That was obvious in the 90s.
But sadly enough, it hasn't worked out that way. Before the Internet Archive anyway.