That people like something doesn't mean it's good for them, or even makes them happy: anything that some people really like and that is undoubtedly harmful can serve to prove that point. It doesn't put social media and heroin "in the same ballpark", it doesn't even say social media is harmful, it just says the fact that some people like it isn't saying a lot in itself. (I might add, especially not when it comes in the form of "you don't love it but people love it".)