Why? There is a perfectly fine questlog in game, including an app to locate the girls.
There also isn't any huge drawbacks in picking the "wrong" Choices. Most of the time it just means that you need to use your powers in the open world to further corrupt the girls.
The only missable I can think of is the sex scene in the fantasy world, but it should be clear what to chose when it happens.
I am confident the lack of a WT/mod is the lack of need for it.
You'd think there wasn't a hint system in-game since I see so many posts with people being stuck lol. "how do I do this/that, get this/that, see this/that character etc" a good in-game (quest log?) is always good to have.
If it is really good, some players need to open their eyes and check stuff out. I like the one Milfy City offers or Milf's Plaza. Other games that have a story (and can finish+ finish other character stories in any order you want) but yeah, the hint systems in those are perfect.
Story wise, you pick what character you want to follow, and the system will tell you what you need to do in order to progress, the item you need (if you need it) and when and what time to meet up with a character for their story/events) if this game has that, that is awesome.
As long as you don't have to grind like crazy, that's also good.