Can you teach someone to be good at what they do? Of course you can study people who are good at what they do. Perhaps other people who want to become good at what they do can learn from that. However, no one will become good at what they do purely by emulating someone else, since what they do won't be the same thing.
Besides. Things like Agile aren't "observing what people who are good at what they do, do". It's a formalized process based on the ideas that some people who are good at what they do have about WHY they are good at what they do. But do people who are good at what they do really know why they are so? They probably don't! Besides, they are going to mix in all kinds of things that they think they do, or they think they should do, or they think that good people they learned from did, in that formalized process. In the end, the process they describe may sound good to them, but have very little to do with what good people actually do or should do in any particular circumstance.
Besides. Things like Agile aren't "observing what people who are good at what they do, do". It's a formalized process based on the ideas that some people who are good at what they do have about WHY they are good at what they do. But do people who are good at what they do really know why they are so? They probably don't! Besides, they are going to mix in all kinds of things that they think they do, or they think they should do, or they think that good people they learned from did, in that formalized process. In the end, the process they describe may sound good to them, but have very little to do with what good people actually do or should do in any particular circumstance.