It's not always about knowing things in and out. I am in a position where I need to know a lot about a lot of things. If developers come with some new tech and want to do xyz. It's very helpful for me to know what xyz is. If non technical people or management comes with demands abc I need to know the bounds of it.
It's not great being in a meeting or on a phone call and not knowing what the other person is talking about. Not only does it make you look uneducated but it makes the other people lose respect for you.
To do what I want I don't need to know everything about a topic. But knowing the basics and its existence goes a very very long way.
I know a good bit about a lot of topics. Then in my specific field I know a lot more in depth.