The problem is that there's no reliable way to identify who mined a given block, so you can't simply have the network "ignore blocks from the attacker." The coinbase transaction may contain identifying info (e.g., pool name) but it's not mandatory nor authenticated.
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If we're talking about a fork, couldn't a fork just ignore the attack? The normal miners aren't forced to use the attacker's blocks after all.
The problem is that there's no reliable way to identify who mined a given block, so you can't simply have the network "ignore blocks from the attacker." The coinbase transaction may contain identifying info (e.g., pool name) but it's not mandatory nor authenticated.