Because some games cater to the uguu desu waifu crowd and others do not. The ones catering to that crowd tend to get by more on their identity as anime games rather than functional gameplay mechanics.
I like sienen stuff. I have watched, read, criticized, and analyzed more anime than most. Heck, I literally just wrote 10-15 pages on Satoshi Kon's oeuvre. I like anime, particularly, as I said, sienen stuff. But I've been dissatisfied with the general discourse around animes, particularly the waifu bullshit, for quite some time. I'm not really wild about the moeification of anime.
I don't mind people being into it. I don't mind talking about it occasionally. But the specific complaint as it relates to Steamgaf is that it feels like it's increasingly taken center stage the past few months to the exclusion of other topics.
So no, there's no reason to see this as an attack on anime or anything. Nobody's demanding you stop enjoying what you enjoy. Just asking if we might turn the noise down a bit.
EDIT: It's the feeling that waifu anime bullshit overwhelms the rest of the discussion to the point of actively driving some people away that's the problem. Steamgaf should feel free to talk about whatever, and I know some people, myself included, feel less free to talk about things than the waifu crowd. The desire is for more diverse discussion, rather than just one specific type.