Right now, I believe we're seeing that the big general-purpose models outperform approximately everything else. Special-purpose models (essentially: fine tunes) of smaller models make sense when you want to solve a specific task at lower cost/lower latency, and you transfer some/most of the abilities in that domain from a bigger model to a smaller one. Usually, people don't do that, because it's a quite costly process, and the frontier models develop so rapidly, that you're perpetually behind them (so in fact, you're not providing the best possible abilities).
If/when frontier model development speed slows down, training smaller models will make more sense.