In a load balanced network with multiple web nodes, modifying the htaccess can be unpredictable since you may write the rule to the htaccess only on node1 and then it may not exist when node3 tries to remove it.
If you need to block at the server level, it might be more effective for WordFence to log the attacks somewhere and and use something like fail2ban to monitor those logs and block IP addresses at the server firewall (iptables) level based on similar rules to your WordFence settings. That way fail2ban handles the actual add/removal of the IP block rather than WordFence.
