Why is there no FFmpeg-like CRF value setting for H.264 and HEVC in Apple Compressor?

I was recently trying to get into using Apple Compressor as the final encoding/compressing step in my video production pipeline. (I came from using ffmpeg on the command line, but the UX is way better using Apple Compressor, and I do not do it frequently enough to remember all the specifics of the ffmpeg API.)

However, I had gotten used to simply setting a crf (constant rate factor) value based on my own visual preferences, and not having to worry about adjusting the specifics of the bit rate based on the visual content of the footage. I was wondering whether anyone knows why these crf values seem to only exist in ffmpeg and not any of the other encoding softwares (such as Apple Compressor, Adobe Media Encoder, etc.).

Also, there is the slider named “Quality” present in the video settings when setting up the preset, but (at least for me) it is always greyed out when using the H.265/HEVC encoder, and I am also not exactly sure what it would be referencing. (Presumably general visual output quality?)

(Figure: Taken as an excerpt of the “video” tab when adjusting the setting for a specific encoding preset.)

I would appreciate any more information anyone can contribute on this matter as I am mainly interested in learning more about how the internals of video encoding work.