This is a pretty alarming concern, there is an alluvion of new technologies right now, and no one can keep up with everything, as a fairly new developer I always try to jump on every new technology that promises to make my life easier, however I'm quickly learning that there is no silver bullet and that the developers of technologies that we know and love learn about their weaknesses after they are out there being used by many. Since a lot of points have been covered already I just want to add a thought: Your product website or whatever is unique to you, so no single product, framework or library will exactly match your needs, and also you only have so many days or years to come up with something to show for, so a great ability these days is to come up with a way of integrating a technology and making it yours, fit it to your particular needs. In order to achieve that, understanding the tools you'll use and why they were built, will get you a long way ahead.