ELI5 - Time Series LLMs

I’m reading through this paper and I’m struggling to build an intuition as to why/how a pretrained LLM should outperform other time series algorithms. Does anyone here have an intuitive answer?

Also wondering about data leakage if the source dataset (M4 benchmark) was included in the training data for any of these LLMs.

algorithms benchmark build data data leakage datascience dataset intuition llm llms paper reading series through time series training training data