If you want to target lower income people, then I think smartphones are the better choice. They can afford a cheap Android smartphone rather than a small laptop. Smartphones provide the same services cheaper and they're handy to use
I don't disagree with you, but I think the parent's point was that a responsive website covers all three bases, where an app only covers 2 (1 in most cases). Why exclude the laptop when you have an easy alternative that doesn't.