I don't think this attempts to address botnet attacks, but to be fair, there are very few tools that you can just run on a single physical or VPS host that can effectively defend against a botnet. Frankly, most things that aren't Cloudflare (or in the same ballpark) will be ineffective against well-crafted botnet attacks.

This is useful in a defence-in-depth scenario, same as fail2ban. You might be able to defeat the odd hacker or researcher doing recon on your host, and sometimes that's good enough for you.

If you need botnet protection, you shop around for botnet protection providers, and you get a botnet protection solution. Easy as.