tutorials are probably less than 0.1% of the training data compared to actual code, or you mean average project is influenced by basic tutorials?

More than half of PHP's problem was PHP's own online manuals that allowed any Bozo to confidently post idiotic answers and copy other Bozos' idiotic confident answers. It's not like confident idiocy is a new thing with LLMs -- they were trained on it.

Then React turned that confidently idiotic folklore into an ecosystem: every confident answer depends on which year it was posted, which version it assumes, and which of six abandoned libraries it recommends. The LLM blends them into a seventh approach that never existed.

For now, I suspect Svelte's shorter, cleaner history with fewer wrong paths taken and retreated from will mean there are fewer incoherent competing approaches for LLMs to blend together into confident hallucinations.

Perhaps less contradictory training data is better than more incoherent training data.

LLMs may not experience the mind-expanding joy that humans do from using Svelte or the mind-numbing frustration that humans do from using React, but they can inherit the coherent focus of Svelte and incoherent confusion of React without sharing Svelte's pleasure or React's pain.