I do. But think you are drawing a conclusion that you are not necessarily actually reaching.You are basically arguing against basic mathematics, as was simply put by wjemather. This seems to be very much a case of you arguing black is white?
18 holes is better than 9 holes. 17 holes is better than 9 holes. 16 holes is better than 9 holes.....you see where I am going with this?
To extend your above, and earlier 1 hole analogy in the other direction :
you might conclude 1000 holes is better than 18. But without knowing to what accuracy that the extra 982 holes makes to a HI calculation, you cannot say that there is a HI accuracy improvement by play 1000 hole rounds. Similarly withou knowing the loss from only playing 9 rather than 13, on cannot say that the additional 4 holes add any meaningful accuracy.