it's probably fanservice for the female viewers since it's shoujo, whereas Naruto is shonen so if it's in there, it's going to be waaaaay more on the low-down so as not to turn off their core demographic.
Like i was saying, the harem genre often has blatant yuri overtones that also don't go anywhere: they're more like set-piece comedy (e.g. the infamous girl-on-girl boob groping) than actual plot-points. They just have the lesbian-boob-grope scene in there, and it's not elaborated on, nor is it expected to be elaborated on, because that is the nature of the genre. So there might be such a thing as a "genre derail" in just about any genre: if they actually followed up on the typical scenes in an extremely logical way, the entire genre of the series itself would be derailed into a deconstruction of the tropes.
Think about action movies for a second, all the "saved in the nick of time" scenes. Let's make that more logical. Either you'd actually play it safe, or the main characters would quickly end up dead. Either way would be more realistic, but you've either turned it into a very short, tragic movie about the dangers of e.g. not using a seat-belt (with realistic head injuries) or you've removed one of the key thrills of watching action movies: the excitement of all the close-calls.
Yes, there are things that do not make sense in fiction. But that doesn't mean fiction is bad. Telling a captivating story vs a realistic story are two different things. So, not every trope needs to turn into a full-blown plot point. You can complain about that, cut away all the fat of a series completely. But almost any series would end up extremely short then. I could tell you the entire plot of Star Wars in under 5 minutes easily, by removing all unnecessary points.