I immediately tried to find a comparison with ARIMA as well and was disappointed. It's difficult to take this paper seriously when they dismiss a forecasting technique from the 70's because of "extensive training times".
Even then, 500 years of daily data is less than 200k observations, most of which are meaningless for predicting the future. Less than 16B seconds of data. Regression might not handle directly, but linear algebra tricks are still available.
