Spammers have been harvesting email addresses written on the web in plain text since the dawn of the web. We've all seen older websites where the author obfuscates their email address like "author [at] domain.com" or "my email is firstname at my domain" or even use an image in place of actual text. I could say that my email is my hacker news username for both the name and domain, on the dot io TLD. A bot couldn't scrape that, but you could figure it out.