Thanks for inquiring about Wordfence. Fail2ban and iptables run are not web application specific security solutions, they run on the server and operate differently. Wordfence is an endpoint web application firewall that is tightly integrated with WordPress, and as such it can take advantage of numerous aspects of web application security that server applications cannot. For example, the realtime IP blacklist that takes advantage of the Wordfence security network data, implementing a rolling blacklist of malicious IP addresses with active attacks on WordPress sites would not be possible with fail2ban and I-tables. That being said, there are things that fail2ban and iptables can do that Wordfence cannot. We have a number of customers that use both quite successfully. I hope this answers your question.
