People need to use shopping bags because they need to carry groceries. No one needs to use Facebook. If you decide tomorrow that you absolutely hate shopping bags, your grocery shopping is going to be a hell of a lot less convenient. If you decide tomorrow that you absolutely hate Facebook, you're just going to have more free time.
Mithaldu's point, as I understood it, was that shopping bags serve a very clear function and people don't have strong feelings of love towards them. They use them because they work. Same thing with FB (apparently). What this article fails to grasp is that having billions of people feel that they need to use your service is worth way more than people saying they "like" your product.
² ³ Just to head off any possible future complaints about that. Some people do think about shopping bags. I do. I like cloth ones and hate the rest. I'm sure there's also some people who think about facebook. We're talking about the average street person though.
³ Yes, there is no footnote 1, i have no superscript 1 on my keyboard. Please send it if you find it.