Frameworks tend to define the structure of your application, and if you attempt to use two different frameworks together in the same project they'll generally not play nicely together. The problem with frameworks is that when the one you're using is out of date it's hard to switch to a new one because they'll conflict.
Libraries attempt to enhance the power of the underlying platform, but don't impose as much structure on your project. As a result you can mix them or introduce them to existing projects. For example, I was able to introduce jQuery to clean up and enhance an existing old-style web site, without significantly changing its architecture.
I was in the same situation as the article poster a few years ago. I had to create a new interactive website, and had a tough choice to make: Flash or HTML? Flash was still strong, and the only website that really demonstrated what I needed could be done was Google Maps. But I wasn't keen on the vendor lock-in and the nature of the Flash plug in. I went with HTML and the then-immature jQuery. I knew the web wasn't going away soon, and jquery could be replaced if necessary. Fortunately I was lucky there and the choice has served me very well.
If it's not your core product, you can use a framework (and be prepared to live with the consequences). But if this IS your core product, so you need to invest in creating and maintaining your own framework. Your business depends on it so you need to be able to control it.