Theres a few places on the site that talks about the subnets heres a link to the convo Subnets
Basically its to make the data decentralized we dont want all the data be in the same place or same country. Also pervents people from running 100s of nodes in a central place with all the same data, so if there was ever an outage the data would still be located somewhere else.
You should not reject any data coming into your nodes.
Currently there’s no settings for this but im guessing in the furture there will be a way.
Just remember nothing is set in stone as of right now because its still beta and theres lots and lots of testing putting the network though its paces it can only get better with time.