The OMB no longer exists, it was renamed the LPAT. So even appeals being handled under the old system are still at the LPAT, just not under the new appeal system.
Really, what is happening is the OMB is getting rebranded and the range and types of appeals have been heavily restricted. The OMB still exists under the LPAT name and will continue to hear cases for years to come, just under a new name and in a more limited capacity.
The URL is just a relic that they have failed to update - the Ontario Municipal Board name has been phased out.