Guess if it works, you don’t really need fail2ban as f2b pretty much does the same job. I mean it can do more, but you don’t really need to protect against PHP issues, broken wordpress plugins etc since none of that is part of Authelia.
I use fail2ban, as I have SSH running and several other services exposed which come with default fail2ban configurations. And I never got crowdsec running properly. So I skipped it. I think frequent updates and all those things are more important than a web application firewall anyway.