I do agree that the article has other things to say as well. It's not a bad article. But I'm pretty sure that the second quote is supposed to mean that network effects cause larger online services to be more convenient for users. I don't agree with that in general. It's true only in some specific cases where integration of several services makes things more seamless. Your quote doesn't give a reason _why_ monopolies develop. It just states _that_ they do. Also, there is nothing about how they can unravel pretty quickly.