I totally agree Bob .... wouldn't take much for it to read different.... a sloped street for example.
I believe (don't remember creator of dip stick dance), the intent was to get it in the ball park. Your process of checking the oil, just proves you know your X.
Some new owners, would probably over fill with this method.... and I'm not saying its wrong. It probably better for someone, that knows their X. Although a nice starting point at oil change is 3 quarts and some oz.
with the multiple chambers, and pulling oil up with the oil pumps, into the right place for the dip stick... well, we gotta start somewhere. I have read posts by owners, giving descriptions of different years with different dip sticks, and which hash mark to read by. And if you are refined enough to know that about your X, that too is great. But again, for a new owner, we want them to get to know their X, and where is runs right, and they know it.
this brings me to a side note: Bobby Baldwins sold apparently a lot of site glasses. the one that mounts over the lower oil pump. There are a lot of owners that never pull their dip sticks as they totally trust that site glass.
I am living proof, that the site glass doesn't give the owner any idea how much oil is in their X. 525 was giving me unrelated puke issues several years ago. It was puking most of the oil. I don't want to go into detail here on the "whys". But after a trial run, I checked the site glass and the back of 525, was shiney, with globs of fresh oil dripping off. The site glass said it was full. I dumped the oil, .... there was 1 quart in it. 525's puking issue had nothing to do with that chamber.
so with that.... heres a freebie, those site glasses are a very cool look, but they don't do anything more than that.
I sort of lost my temper when I discovered that, and removed that site glass immediately. Believe me, I still like the look but at that time, I was very discouraged.
another freebie on that site glass: keep an eye on it, they have been known to weep, and the glass has popped out on a few thru the years. Just keep an eye on them.
Bruce