After digging a bit deeper into games might historically related to the precursor of Go Some musings on a "reverse" ko rule - #14 by claire_yang, I came to a realization that what we considered as intuitive and as basic like the moment of removing “dead stones” might not be that clear if the original goal of the precursor games are about capturing in the first place.
I feel it is very important to think the acts of “make a move”, and “remove stone when it run out of liberties” are in effect two “actions”. If remove stones that run out of liberties is an action has to be done by the opponent, suicide as we know it is an act to waste the action of the enemy, and would be part of the precursor rule.
It also worth pointing out that the reason I believe the “dead stones” didn’t get removed from the board is older, is it meant there is no “secondary game” under the table, or outside the board in this form. The “captive jar” is in plain sight on the board and part of the game with no additional “captive jar” required, and players could not have cheated if they want to (like hiding some stones to begin with), since the board has to be filled by default, and it would be very clear to know if someone hid stones and not play it.
I also think that when enough of these games being played where stronger players start to realized that they don’t always have to play to the end, and by counting the safe zone to know who has more hypothetical captives to end the game. And this “quick counting method”, might be why we have two-stage of the game, playing and scoring where the latter half originally was just convenience and more advanced gameplay reserved for the “elites”, who are good at math and have extra tools to “record” and count the hypothetical captives. We need to remember digit numbers themselves are inventions appear much later in history, and for a long time in history, education like basic math is also only reserved for elites, and require some extra tools like counting rods or abacus to get it verified.
The comparison of who has more captives with rules required a full board is much easier even if you don’t have those tools, since players just need to check who has a longer captive lineup with intuitive counting.
So I believe the precursor of Go without filled captives quickly diverge from the original full board when they were played by the elite, and then been taught like a type of different games only to nobles at the time, who has the means and knowledge to carry on the “scoring phase”, which is in itself a game of sort, requiring to imagine the game to be played to the last, with extra tools to get it right, and like most modern “game expansion pack”, it doesn’t change the game at all, but only some superficial add-ons to attract “wealthy players”.