Actually i think to give this discussion a fairer argument, one would have to bring up Mr. Sunshine also which was broadcast in 2018, a year after this article was published. I haven't finished watching, but yes it did come across as if a work from a different writer, that drama.
I guess Mr. Sunshine is undeniably taken very seriously because it's setting is war-historical but TKEM is more like historical fusion where she's already decided that the setting is only to mask her Cinderella type of stories after all, thus the shallow-ness in plot and other characters.