That's because you've only read one "genre", the kind geared towards young teens where nuanced conflict was never the point. You've only ever read the manga equivalent of YA, and you don't want to put the effort to find the troves of more mature stories with diverse drama and insights only possible with complex characters undepictable in a story that is one step above a 4-koma. You know on the inside the solution was always to seek more mature stories, but here you are, on a sub-full-length doujin, pretending to criticize a story with buzzwords like 'plot device' and 'trope', when that is as silly as criticizing Garfield for character development. The reason you haven't done so is the same as the reason people in their twenties and thirties don't stop reading YA and shounen, ignoring that tickle in their mind as they wonder why this story written for teenagers isn't resonating anymore: you yourself haven't grown up. Because it's infinitely easier to talk down about 'plot device' and 'trope' on a manga where each chapter is like less than 10 pages long with 4 panels a page, than it is to confront the fact that expecting Dante's Divine Comedy out of a lesbian story without tribadism is another in the long line of excuses you use to avoid approaching fiction you'd actually have to think about.
Really wish this author didn't use rape as a throwaway plot device for some woefully inadequate drama that just fails to excite my sensibilities. I've seeing it everywhere in all the manga I read and in literally almost every genre. This arc has failed to impress me hmm yes.