It truly is and even for experienced developers it can be overwhelming. It is simply impossible for anyone person to be knowledgeable every new technology and/or programming language.

I used to constantly fall in the trap of shallow but wide breadth of knowledge. Something new would come out and I would drop everything and dive right in. It feels rewarding at the time but really in the end has very little benefit (unless of course your a tech reporter).

My advice is to achieve a narrow and deep knowledge base. Pick a few that you feel passionate about and really concentrate on mastering those. It would help to pick those that have a large number of related job openings if its your livelihood. Mastering Java may seem old school, but the number of job postings I still see for java developers is amazing.