Yes, but the material presented in no way makes distiction between potential organic growth of 'delve' vs. LLM induced use. They just note that even though 'delve' was on the rise, in 23-24 the word gains more popularity, at the same time ChatGPT rose. Word adoption is certainly not a linear phenomenon. And as the author states 'I don't think anyone has reliable information about post-2021 language usage by humans'

So I would still state noun-phrase frequency in LLM output would tend to reflect noun-phrase frequency in training data in a similar context (disregarding enforced bias induced through RLHF and other tuning at the moment)

I'm sure there will be cross-fertilization from LLM to Human and back, but I'm not seeing the data yet that the influence on word-frequency is that outspoken.

The author seems to have some other objections to the rise of LLM's, which I fully understand.

there is almost certainly organic growth as well as more people in Nigeria and other SSA countries are getting very good internet penetration in recent years