Are the majority actually writing code like this though? In the case of dynamic languages, this property seems more like an additional consequence of how the language behaves. It's not additional syntax.
I really don't know what more to say about this; if you don't want to use them, don't. ...but if your excuse for not using them is that other people don't, it's wrong.
Yes.
For example, some use cases: https://www.typescriptlang.org/v2/docs/handbook/unions-and-i...
This sort of code is very common.
I really don't know what more to say about this; if you don't want to use them, don't. ...but if your excuse for not using them is that other people don't, it's wrong.