$SITEURL: does it really need to include scheme/host/port?

[aldem]

I guessed that migration prompted your post.

Well, not exactly

I just want to know, are there any objections to change to relative and (semi)automatic $SITEURL, and it seems that the only reason why it is absolute is because no one did it relative - I am right?

I see some potential in GS, so I am trying to investigate how close my thinking is to thinking of GS developers and users - if close enough, I could share whatever I do to impove things, if not - then I simply will do it for myself and not bother anyone else