TAS is cool as people can use it to find the most optimal way to finish a game. Sometimes tricks are too hard for people to do or at least they are believed to be to hard for people to do. Sometimes TAS “only” tricks end up being done by people.
The whole point is that it's a TAS. This is a whole category of speed running. It would be cheating to submit a TAS as an actual speed run but submitting a TAS as a TAS is clearly not cheating.