Some do it just to meme or be funny. Especially ones that make these kinds of posts.
The ones you really have to worry about are the ones that get mad when you mention something about a character that is not accurate. They will publicly execute you. Worry about those ones.
I don't know the context of the meme but i guess she doesn't look like that in the game or something? They did their waifu dirty? These jokes seem quite harmless and light.
The thing abaout "waifu culture" is that most people do not actually think or act like fictional anime characters are real people. They do it to troll, or be funny, or act stupid, whatever. Like circlejerk subreddits or other online boards where there is some joke that gets perpetuated that everyone in the community thinks is hilarious but everyone outside thinks is stupid.
Yes, there are a tiny few that do, but not a significant number of people actually think that way.
In the game, she supposedly has well defined muscles, and slightly larger breasts I guess? I haven't looked at her enough in the game to really remember it by heart.