I agree with your first paragraph. I don't know about the second. I have aways been a water-baby, but I had real fears about mask clearing. I mean big ones. It took me several years to really clear them up. I teach mask skills fantastically because I absolutely get it. I know all issues there. Many instructors can, (all should), be able to read their student. That is a key part of being a great instructor.
IMHO, if mask clearing took you several years to clear up the fears, you fall into a small minority category of Instructors. It may not be the same small minority as Walter falls into but how many scuba instructors do you know who took years to "master" mask clearing? My definition of a "water comfy decent swimmer" would be someone who could not be challenged by mask clearing the very first time.
Your evidently different definition of "water comfy decent swimmer" does not change my feeling that the vast majority of scuba instructors really do not understand the fears of the typical struggling OW student.