Cannot use gmail as a local repo?

[Ivan Semin]

Hello!

I have written recently about my experience using offlineimap to
backup gmail account. Now I had another idea - what if I try to use
gmail as a backup storage too? I have 8GBs of emails (99% of the
limit), what if I create another 8GB gmail account and copy all email
there. Then I could delete some mail from the original account.

However, offlineimap says I cannot use gmail as a local repo. In other
words, gmail to gmail sync is not possible. What is the reason for
that? Also, nobody could clearly answer me about the difference
between remote and local. Is there any difference?

I am currently trying the sync I described anyway, just set up the
backup gmail account as imap.