HEIF has been released (and actively developed) for over two decades. It received a huge boost of attention in 2017, when Apple made it the default image format in iOS 11. As a result of that, many mobile-first users author their images in HEIF (knowingly, or not).
Making new formats as common as todays mainstays necessitates them being accepted as one you can use for all purposes. Because of that, we believe HEIF should be allowed as a source format.
The test is simply if each format is an accepted as source file for optimization. This is, by nature, custom to each tool and service.