The question that Chinchilla tries to answer is: for a given training budget (which you can think of as dollars or FLOPs), what is the optimal trade off of model size and quantity of training data to get the most performant model? Build a large model and train with less data, or build a smaller one and train with more data?
However, another consideration is minimizing total lifetime cost of the model: training cost + inference cost. You could train a model for longer (costing more) in order to get a given level of performance from a smaller model that will be cheaper for inference, or vice versa. For any given projected model lifetime inference volume, there is going to be a different answer.
It's not that Chinchilla-optimal models stopped making sense, but rather that this sort of consideration has people willing to pump more money (tokens) into smaller models to reduce inference cost for that level of capability.