The main LLMs are improving fast enough that building an adjacent business is hard.

For example, a business to finetune models to specific use cases, or a carefully calibrated UX flow to help squeeze out higher quality React apps out of models.

But then a new model comes out that was directly trained on doing that use case well and it leapfrogs all of your linear improvements, obviating them.

"Proprietary tools to squeeze slightly better quality out of a model" doesn't seem like a great business.