I understand what you're saying, but it's very narrow. It's only oral communications, not written or other communications. It's only when it's initiated by the lobbyist—not someone else—and only when it is, of course, to a designated public office holder.
In other words, what is allowed is secret lobbying. If the lobbying occurs on a street corner, as opposed to in the member of Parliament's office, and if it was initiated by no one, then it's not reportable, and therefore it's secret.