Hi @The Creative Tablet
This is a very interesting question, and one that goes beyond WordFence specifically.
The BlogVault guys wrote a very interesting article about it actually: https://blogvault.net/does-wordpress-security-plugin-secure-your-site/
Does WordPress stop hackers or is it just a secondary solution if and when you are hacked?
Is a very big question, the response could easily be turned around with:
What kind of hackers?
WordFence seems to have a fairly decent brute force features, which could be argued is preventing attacks. But the attack spectrum is so diverse, brute force attempts are but one attack vector to be concerned with.
The article articulate this point very well.
All the best,