Eklektikos said:
It makes it no harder whatsoever. There is never any guarantee that the DP in a turnchat hasn't spent the preceding three hours doing god knows what with the game. There is never any concrete guarantee that they are doing what they say at the time they say they are doing it, nor that the turn 0, 5 & 10 saves weren't produced prior to the beginning of the chat. In a chat as in a closed session, the citizenry are entirely dependent on the honesty of the DP.
It's much harder to fabricate a "real time" log if you already played the game. Reason? People are going to ask unexpected questions, like, "See if the French have anything to trade now that they're at war with the Aztecs" (i.e., maybe the French and Aztecs were trading something, and now that trade is broken). Or, what if the trade advisor wanted to see the save after a potential trade opened up on say, turn 3, but the DP had really saved turns 0, 5 and 10 already. With a public chat, it makes it much harder for the DP to cover up those things that might come up during the game.
Suppose something like this happened... (a hypothetical scenario).
We are the Byzantines, and have 5 sources of Ivory, and the Maya have 2 sources of ivory. The Maya are trading ivory to the Koreans. Other than the ivory trade, Korea (with 13 size 10-12 cities), has NO luxuries (meaning they value the luxuries highly, and we have good relations with them -- no rep hits). The Koreans are known to be making atleast 45gpt (It's the middle ages).
During the course of the 10 turns, the DP plays ahead before the turnchat. The DP declares war on the Koreans on turn 5 (after saving the game -- or, perhaps does so sooner, and has 2 versions of the save), and later signs a peace treaty on turn 10. The purpose is to capture a city that has horses, and blame it on a culture flip. Now, the Maya happen to break a treaty with the Koreans and declare war on the Koreans on turn 6.
During the chat---
The DP goes through turn 5, pretends everything is fine. Turn 6, the DP says that Pusan has culture flipped (when in fact, it was really captured that turn, with 3 resistors in it). Also on turn 6, the Maya declare war on the Koreans. The trade advisor is present, and wants to see the save to find out if any trade possibilities are available to trade ivory to Korea. Assuming everything has gone as planned, Korea should be at peace with us. Up to this point, the DP has made no mention of the war.
What's the DP to do?
1 - He could say, "Oh yeah, they declared war on us". But, then, how does that answer the fact that maybe, the DP already defeated 25 Korean units, and we have a city with resistors in it?
2 - He could say, "I just checked, and there's no trade deal possible". This is why we should let the advisors and citizentry examine the save. Maybe the Trade Advisor might find something out, like lowering the science rate might open up a trade. Korea's making a lot of money, and we have no rep hit, so something is possible. This would be just plain fishy.
3 - He could switch to his alternate save. But what happens when the Maya don't declare war? Maybe the war was declared do to the DP declaring war on the Koreans (AI dogpiling).
Turnchats help prevent this by making it harder to do things like this.