>>35982008self-insertation - they were attracted to her design from XY, latched onto her anime portrayal and in combination with Ash being more competent than most of Kalos (like they are with the games), got confused along the way as to what was actually portrayed and what they envisioned in their heads.
Then pic related happend, Ash fucked back off to Kanto to regroup for the next series and they were left ultimately blue-balled, no championship title, no on-screen kiss and no hope of seeing their waifu again. Small wonder they're lashing out so badly - again mistyfags 2.0 for not being able to get over the fact she was only ever a one-series wonder.