That’s actually where Reddit is useful as a training corpus, because different subreddits are at different levels of quality. It’s pretty easy to identify the high quality ones for training answers, and the low quality ones are excellent for training basic transforms (making sense out of an input that is niche and flawed in some way).

There are very few other sources of lightly structured training data that span all of humanity broken down into topics, graded to different levels of quality. Over time, the data will become less relevant as society moves on, so a living training set is important.

Having said that, Lemmy could prove to be an even better training source for expert system LLMs, as there could be curated instances of high quality with the ability to pull in more federated data as needed.