Slack: HTTP Strict Transport Policy not enabled on newly made accounts

Hey As we know that the HSTS prevents MITM against SSL. I just checked the headers of the account i created localhost.slack.com SERVER RESPONSE: 200 OK Cache-Control: private, no-cache, no-store, must-revalidate Content-Encoding: gzip Content-Type: text/html; charset="utf-8" Date: Wed, 03 Sep 201...