Writing "/etc/hosts" breaks the Substack editor

This isn't a "security vs usability" trade-off as the author implies. This has nothing to do with security at all.

/etc/hosts

See, HN didn't complain. Does this mean I have hacked into the site? No, Substack (or Cloudflare, wherever the problem is) is run by people who have no idea how text input works.

> is run by people who have no idea how text input works

That's a very uncharitable view. It's far more likely that they are simply using some WAF with sane defaults and never caught this. They'll fix it and move on.