you seem to be mixing up that mining pools expose tcp/8333 and if one pool's full node is attacked - many miners are caught in the crossfire unless in some type of special firewalled whitelist.
> you seem to be mixing up that mining pools expose tcp/8333 and if one pool's full node is attacked - many miners are caught in the crossfire unless in some type of special firewalled whitelist.
Mining pools don't typically expose tcp/8333 in a way that makes it easy for them to be targeted and when they do they typically have redundant nodes and other mitigation measures in place to ensure reliability.
There have additionally been high speed optimized block relay networks used in the past by mining pools, although I don't think they are used anymore due to the public p2p network being much faster and more reliable than in the past due to various protocol improvements.