[franga2000]

Where did you get that idea? These certs have always been intended for any TLS connection of any application. They are also in no way specific or "designed for" HTTPS. Neither the industry body formed from the CAs and software vendors, nor the big CAs themselves are against non-HTTPS use.

From https://cabforum.org/

> Welcome to the CA/Browser Forum > > The Certification Authority Browser Forum (CA/Browser Forum) is a voluntary gathering of Certificate Issuers and suppliers of Internet browser software and other applications that use certificates (Certificate Consumers).

From https://letsencrypt.org/docs/faq/

> Does Let’s Encrypt issue certificates for anything other than SSL/TLS for websites? > > Let’s Encrypt certificates are standard Domain Validation certificates, so you can use them for any server that uses a domain name, like web servers, mail servers, FTP servers, and many more.