API Deprecation Question

Hi, I've got a question regarding the deprecation of API's. I've developed a script which allows the automation of backups for resellers, it currently uses WHM API 1 to list accounts and cPanel API 1 to run the backup. I noticed pretty quickly when you released new functions within the UAPI to run the full account backup, knowing cPanel API 1 is long deprecated I chose to start researching/integrating it. What I realised is that while cPanel API 1 is long deprecated, WHM API 1 isn't and there are no signs of any of the functions of WHM API 1 being moved into anything else e.g. UAPI. Can I ask why and what is the reasoning behind it?