It's not a funny meme, it's making fun of something that happens to countless people around the world. Dude made a more serious comic one time and everyone went crazy and parodied something that probably was very personal to the author. You kinda don"t have empathy if you actually thought "I should meme on a comic about a miscarriage".
The meme is not about the miscarriage but about how tone deaf it was. So your point is actually why the meme started being a thing, mocking the comic itself. That's the context of it as far as I'm aware
Nope. All it boils down to is "funny comic cannot be sad ever". People expected the artist to make everything the same, always. When they didn't, they memed it to oblivion because it was trendy to do at the time.
No. It wasn't executed well. Plenty of other popular comics, tv shows, whatever have successfully blended sadness or other powerful emotions to their comedy. This one just failed. So it got memed.