Why is the line terminator CR+LF?
https://blogs.msdn.microsoft.com/oldnewthing/20040318-00/?p=40193

If you go to the various internet protocol documents, such as RFC 0821 (SMTP), RFC 1939 (POP), RFC 2060 (IMAP), or RFC 2616 (HTTP),
you'll see that they all specify CR+LF as the line termination sequence.
So the the real question is not "Why do CP/M, MS-DOS, and Win32 use CR+LF as the line terminator?"
but rather "Why did other people choose to differ from these standards documents and use some other line terminator?"