From Unreal Engine 5.1 onwards, you will see a message that says that these kinds of inputs are deprecated (meaning that eventually they will stop being supported).

In section 11, we will replace the inputs created in the old way for the new Enhanced Input system and I will explain in detail how they work.

For now, I find it very useful for you to learn how the old system works because it's more simple, straightforward, works similar to the new one, and there are a lot of sample projects that still use them.