Ancient stone scoring practices used territory counting shortcuts (while still preserving the same result as stone scoring)
Another interesting point from the article is that the author goes through historic scoring examples for several old game records that have been found in literature. Even though these games are played with stone scoring, play stops apparently early with not even all of the dame filled. It almost appears as if they were playing with Japanese rules. However, the reported scores show that ancient players used territory counting shortcuts that still abided by (and gave the same result as) stone scoring principles.
Instead of filling in the board with as many stones as they could, they stop early and count assuming that players would do so (and properly deduct the group tax implied by stone scoring). They don’t care about getting the absolute scores correct, but only getting the score margin correct. So, when there are only an even number of inconsequential dame left (i.e., those that don’t create teire situations), those can be left unfilled without changing the scoring margin. Further, instead of counting by stones or area, they ensure that both players have played an equal number of stones, and then count territory with deductions for prisoners and group tax. This count gives the same scoring margin as if they played it out fully and performed stone counting.
Other obsolete rules regarding dame from seki positions
On a different note, the dame that must be left open for seki also allowed for an interesting wrinkle in some older rules sets. Under all modern area scoring rules, the players scores will (in most games and when all dame are filled) sum up to 361 (on a 19x19 board), since the principle of area scoring is simply about dividing up the board by which points are occupied or fully surrounded. The exception is when there is a seki, which forces some points to remain unfilled and neutral, counting toward neither player’s score. Interestingly, an older version of the Chinese rules (I’m not sure when this was abandoned) and an older version of the Ing rules would pro-rate the scoring for the neutral dame left over for seki. Basically, each player get fractional credit for each dame based on how many stones they have adjacent to it. This keeps the sum of scores equal to 361 (which some might view as more aesthetically pleasing), but introduces the possibility of fractional points from board play (which some might view as less aesthetically pleasing).
Consider the following seki for example:
Under modern area scoring rules, white has 12 points from this seki (10 living stones + 2 territory), while black has 2 points (from two living stones). Of course, black would also have points from the surrounding black stones and both players would have more points from the rest of the board, but that’s not the point of this example.
However, under the older pro-rated dame rules, black would get 2/3 of a point from each of the two dame (since black has two stones adjacent to each dame point, while white only as one stone adjacent to each), and white would get another 1/3 of a point from each of the dame.