Like I said before, the real problem with moe has more to do with making characters more desirable and interesting than they really are to the point of running the risk of sexualising them. It doesn’t always happen but it can and do given the opportunity. To explain why moe’s a problem in anime it’s going to be like wanting characters in stuff like Arrow to be made more interesting.
It’s like you feel no matter how invested you are in her, you find her boring in some regards and wish she’s more interesting (whatever that means). To the point where you wish she’d wank with an arrow whilst reading a romance novel (if she’s bored from having sex with Oliver). It’s not the same as say wanting her to have hyena features but it can feel like it because you don’t find her desirable enough.
While it’s not unique to anime, what’s remarkable is how sexualised anime’s become due to proto-moe/early sexualised things like some of Go Nagai’s works, fanworks (almost always far more responsible in sexualising characters) and the like. To the point of including paraphilia like sissification (anime traps), sadism of any kind (Midori) and paedophilia. In fact, these three were included fairly early on.
The last one having begat works like the Lolita anime and the like. That’s how sexualised anime’s become though other animations are beginning to catch up in here so.