ethereum intentionally split by banning opposing nodes (google it: --oppose-dao-fork)
It didn't ban nodes. That instruction simply installed an ETC client or an ETH client. With a different protocol. It is as if you could use a bitcoin core client, and give the instruction --run-litecoin.
And transactions from one chain WERE transmitted to the other chain, which caused a lot of surprise. But this is normal: miners wanted the fees, so they went LOOKING AFTER valid transactions (not on the network, but on the block chain !).
lol bitcoin and litecoin are different coins. etc and eth are different coins. they have their own networks.
they have their own mempools.
they do not intercommunicate. because they only connect to the side they like and ban from talking to the side they dont like. to avoid the orphan drama.
yes i agree initially it was a consensus/controversial event. but then turned into a bilateral split. by nsuring they avoided the orphan drama by avoiding inter-communication