One of my favorite articles on this topic, "About those vector icons", goes into this issue and many more flaws in much more detail. There's nothing fundamentally wrong with vector icons, but it's not all that's needed for a one-size-fits-all solution.
showing some image using fewer and fewer pixels is like trying to summarize some text using fewer and fewer words, at some point it requires intelligence, at another point it's an artform
https://www.pushing-pixels.org/2011/11/04/about-those-vector...