understanding the use of additive or multiplicative scale of timeseries?

In python, by using seasonal_decompose we find whether the given time-series is having multiplicative scale or additive scale data.
But, what is the use of finding it. I haven’t seen it’s use in building models like SARIMAX or ARIMA or any such models. Can anyone explain its use and where it is used? I’m new to time-series concepts.