I like the term Jack of all trades master of some. Another term for this is skill stacking.

Here's an example. Lets say you are a pretty good programmer. Maybe not the best but that is a specialty. But also you are a good communicator and are very good at organization. Well now you are probably worth two great programmers at least on some teams. Many years ago one of my managers encouraged me to do public speaking. I had done a bit before but never seriously. She had me do presentations in front of educators. Then I started running a local developer meetup and doing talks to other devs on a monthly basis. Eventually I spoke at some tech conferences as well. This led to me being a key leader on teams, speaking to clients, going on sales trips to land new clients. I ended up learning other skills beyond just public speaking. I believe specialization is good. I've done it for a long time but I also think there is no reason why you shouldn't also try to find at least two complementary skills that you can get proficient at. Writing is a great one for almost anyone.