The implication of this topic seems to be that if a course is not considered to be a top 20 or 25 course (maybe top 50), then that course is not worthy to host a major. There are currently over 15,000 courses in the US. If a course were to be considered in the top 300 of all courses (per its architecture quality), that course would be in the top 2% of US courses. I do believe that all courses that have held the US Open or PGA Championship over the past 30 years would be judged by most knowledgeable observers to be in the top 2% of courses in the US at the time of that major.
Obviously a great course may be deemed to be inadequate to host a major due to other reasons (e.g. logistics, regional weather during that time of year, club policies, etc.). Also, I imagine courses have been selected to host a majors, over architecturally better courses due to other considerations outside of the quality of architecture or the quality of the championship test offered by that other course (e.g. visiting a different geographic region, visiting a non-private club, potential higher revenues, etc.).
So while architecture quality may not be the TRUMP card in choosing host courses for majors, and although some courses that have hosted majors may have some strong deficiencies in their architecture that bother some on this site, the record very strongly endorses my theory that the courses that host majors are almost always in the top 1% to 2% of architecture quality among all US courses. Too often a course gets downgraded for not measuring up with the top 20 to 50 of all US courses, causing some very good courses to be deemed as being average just because they are not GREAT.
[I accept that ranking a course to be a top 20 or top 300 is very arbitrary. However, since this topic is about if certain courses qualify as great architecture, then the whole topic is dealing with a certain amount of arbitrariness. To avoid the arbitrariness of the “quality” of a course’s architecture, would result in this whole topic being completely irrelevant. And this topic may be irrelevant because of that arbitrariness.]