Relevance of RFC2228

Relevance of RFC2228

I have just read RFC2228 and clients like Filezilla still seem to support it.

Te RFC says

 The following new optional commands are introduced in this
   specification:

      AUTH (Authentication/Security Mechanism),
...

So now i am confused. I use SFTP and FTPS since some years and now i wonder what is the relevance of RFC2228 today? Was it a predecessor of SFTP and FTPS which is obsolete now?

Let me explain what i mean:

When i use FTPS to encrypt my entire FTP-traffic through a TLS-tunnel, do i still need the commands described in RFC2228 for anything?

Are there any security-issues when someone use only RFC2228 (without SFTP and FTPS)?