Yeh generally it’s about reach. In the case of NWS Technically its not exclusive as their data and messaging is distributed by other channels, including traditional, and their own site(s). But for ticking the social media box they’re likely to select the platforms with the most reach. Dissappointing that its only the one if that is the case, but the US is the land of officiated orthodoxy I’ve found. There are advantages sometimes - less triplication of labour in the case of humans needing to curate social media output for example. Bring on interoperability of platforms, please.