Not sure if this is the case here, but lots of weather APIs cost money, so if they tried to integrate the full process themselves they would no longer be provid

Not sure if this is the case here, but lots of weather APIs cost money, so if they tried to integrate the full process themselves they would no longer be providing a free service, and instead losing money. So by outsourcing the download portion to you, each IP may get a few free downloads and then you just provide the data yourself saving the creator money and allowing the tool to be free...