[Resource Timing] Why does connectEnd exclude the SSL Handshake?

I understand why the spec states that connectEnd excludes SOCKS
authentication etc., but don't quite understand why it excludes the SSL
Handshake

"connectEnd must include the time interval to establish the transport
connection. It must not include other time interval such as SSL handshake
and SOCKS authentication."

I've had a hunt back through the archives but I couldn't find any reference
as to why.

Is anyone able to explain?

Thanks

Andy