Why do some open source projects not allow to report issues in a public issue tracker?

Those projects require the issues to be reported via email, and the issues may be forwarded to people in a mailing list.

Users may repeatedly report the same issue if there is no public issue tracker, as they have no easy way to know what has been reported before. The project team members need to spend extra time answering those repeated issues.

Some projects do have a public issue tracker but the issues are still reported through email and they are posted by the project team only after filtering. It does not allow anyone to report directly in issue tracker (example: SVN).

Such arrangement is not transparent nor open, which I think violates the philosophy of open source. And it is outdated.