@jdobbs
You may find this discussion interesting:
https://forum.doom9.org/showthread.php?t=180438
At the end CRF means just constant rate factor and provides a 'constant quality' for a particular encode. It is not an absolute quality measure and hence even for the same CRF the quality differs from source to source and between different encoder settings.
But yes, the behavior for x264 was more logical than it seems to be for x265.