No you are misinterpreting what he is saying. He is saying that COMPARATIVELY saying something generic for a VN is more useful than saying something generic for a sandbox game. For example:
Consider a dating sim kinetic VN that has days. Saying something like "Added 1 day for character x" is about as generic as you can get and I see devs do this for VNs all the time. As a novel it is all about the story so any more information would tread on spoiler territory. But you have a really good idea of how much content got added based on how long it took to play previous days and can easily determine if you want to play it again or wait for more updates.
Now consider a sandbox game like this. Saying something generic like "added some quests" doesn't tell you a whole lot, especially for a game like this with a massive amount of characters and affection points that have to be grinded. Were the new quests for characters you were interested in? Is there actually any porn content? How big of quests are they? Are they just fetch quests to raise affection? You have no way of determining if you want to come back and play it that update.
So his point is valid, saying something generic for a VN is a lot more useful than saying something generic for a sandbox so there is a reason why the dev should be more informative in their changelog (which they have
said they will be). Not everyone is going to want to play every update regardless of how much content got added, or waste the bandwidth if they are on limited download plans that are stupidly common in the US.
P.S. Also you are the one contradicting yourself. You're statement of "You just have to follow the questlog" proves his point that the changelog is useless. The whole point of having a changelog is to see what has changed to determine if you want to download the new version. You shouldn't have to download and play the game to determine if you want to download and play the game.