If we are, in fact, all knowing creatures that is true. However, experimenting with things that we have not experienced can open our eyes to possibilities that we had not considered when we set our goals.
Green Eggs and Ham.
At best estimate, I've played with over 200 DMs. I've watched thousands. I have stolen things from most of them, whether it was an administrative technique to run games more smoothly, an acting technique that conveyed something to the table really well, an idea for a new spell, a new monster build, or a physical prop (ok, I didn't steal the prop - but I did go out and buy my own). However, Matt Mercer is one of the 5 DMs I have heard run games the most - and I have stolen more things from him than from any other DM despite having come across his games nearly 40 years after I started to play and establish my methods. He is excellent at:
1.) Handling players that do not know the rules without making them feel bad.
2.) Using silence and pacing to create a more dramatic presentation.
3.) Misleads.
4.) Building upon what players try to do rather than negating it.
5.) World building (he started with one town and slowly built his entire campaign world from it in an organic way).
6.) Evolving the complexity of his campaign as the players explore it.
7.) Writing the characters into the story rather than letting the characters explore his story.
In short, while he uses his acting skills very well, he is also excellent at the project management skills that make an exceptional DM.
Even if you do not want to play a style of game that mimics Critical Role, you can learn a heck of a lot from listening to him DM. I really wish that they'd add a show to Critical Role that talks about some of his techniques and then shows clips of those techniques in practice.
I haven't watched the show much, but I did notice that Mercer is pretty well the only 'Internet GM' other than Matt Colville who gives consistently good GMing advice.