because in bcash land they can convince the miners to include tx's with 1 satoshi fee, so they can bloat their chain with all kinds of junk like yours.org Good luck doing that in ethereum land.
https://www.yours.org/content/first-utxo-commitment-on-testn...
A full node won't help you against an eclipse attack. And also not against a sustained 51% attack since miners can mine empty blocks on the minority chain, halting it.
A full node is good for increasing your privacy, disguising what addresses you're watching, but that's all.