It's multifaceted. It might be fine if you own a large enough home that you can have a dedicated working space, with a door.
Even without kids, I find it extremely difficult to work from home without a dedicated space. If I try to work from the living room, I end up doing living room things (like playing video games).
For some people, though, the idea of engineering your environment to change your behavior is either impractical or unheard of, which is what I think gives these people the general impression that "working effectively from home is impossible."
