I thought that some were in disagreement with the changes in handicap calculation which is to now include all rounds except those that are pure practice playing multiple balls, etc. The statements I thought made it their position that only stroke play competitions should be included in handicap calculations. If I am incorrect then I am sorry for any misstatements on my part.
When the last major change was made to unify the handicap systems, I was told by a staffer of the USGA and two or three senior volunteers with interest in handicapping, that the USGA agreed to exclude unaccompanied rounds as a concession to the R & A for its inclusion of non-competitive rounds to calculate a valid index. It was not a matter of either being optional, though players under R & A's system had some lead time, a year as I recall, to comply.
I made the argument against not posting unverified rounds (playing as a "onesome") that integrity was a cornerstone of the game and that I couldn't remember an instance outside of a formal competition where cards were traded and two signatures required to post a score. Nevertheless, the concession was made to unify the systems, but it has been well-known that in the UK and Australia, golfers ignore this putative agreement.
Not being a competitive golfer any longer, I could not establish a meaningful handicap by only posting competitive rounds. That being the case, when I've played in the UK, it is very clear to me that USGA handicaps are 3-6+ strokes lower (conjecture) than those of my local counterparts. It is not a big deal in "friendly" matches like in the Buda, but opens such as the Carnegie Shield is another matter all together, even before considering the home turf advantage.
All of this handicap stuff was not a concern when I was young and could get into most local events and national qualifiers (subject to the 8-10 stroke performance rule). Now that I sport a 9.5 index, it is of some significance as I go against young Europeans and Ausies playing off a 15 who outdrive me by 50 yards with a 3-metal and I'm giving 5 strokes. It is not much of a competition if we're working from different bases, one reflective of tournament performance, the other mostly on casual rounds, the majority played on a home course.
I don't know that there is a solution outside games played by known parties. Though it won't work in the U.S., I believe the R & A system is superior.