As QM (non-relativistic) is a really mature field, all the theoretical activity (basic systems) have been built and tested against theory. The theory is basically “finished” all that remains is to use the theory to analyse complex systems which can only be done computationally.

Many people might intuitively have the other opinion as they imagine QM to be some “ground breaking” new thing for which super smart theoretical physicists are trying to find new equations. They don’t know that this field is “mature” and we’ve moved on from testing it.