You don't really need to beat everyone to progress, only a few characters give you a GO for losing. Naga gives it to you, and only first type of them. Fire Elemental does. Demon King does. Puca can. Urka may do.This game could be much better if you receive XP via sex wins also. It basically forces you to play boring and the only viable high AGI build, and to skip all the content because you need to kill everyone to progress.
Also, five characters can give it to you, but you have ap option currently to resist and ignore it. So, what keeps you from not earning XP?
Considering scenes you don't see, well, visual novels always rely on saving and loading multiple times to check the branching options you have. Win, lose, choose this, choose that. What can be done about a core of textual games? Detroit was also made the way you need a lot of replays to see all the interesting alterations in plot you could have.