If there was an AI model that ran locally on a PC for basic things and cloud sourced computer power for more complex tasks, all of these data centers would become obsolete in an instant. All of the invested capital and materials wasted in a flash.
Edit: lots of great counter points in the comments.
As a statistician who has implemented models nowhere near the scale, and as someone who has experience in distributed computing, a lot of the actual work comes from global optimization, which means that all the state has to be communicated somehow. Now this state can be distributed, but it needs to exist, so now you need to have the same resources required to train the model, plus the resources required to shuttle the state around in a distributed manner. It’s cheaper and faster and more ecologically friendly to build better hardware.