@johnpoz is correct. Having an IDS/IPS or pfBlockerNG is not mandatory to secure your data. They are just two of many different tools that when used in the right context for the right reason can enhance security. But they are not required. It all depends on the specific network that needs protection and what constitutes "normal" traffic on that network.
My personal opinion is that most small home networks really don't need either package. The very best security practice is simply being committed to keeping your software packages updated. This means the firewall itself and of course any client applications on PCs, tablets, phones, etc. That simple practice goes a very long way towards enhancing security.
If you have network users at home that are what I call "free clickers" (meaning they will click on any link anywhere .. ), then it might be helpful to have some additional tool such as an IDS/IPS or pfBlockerNG to help protect those users from themselves. On the other hand, if you have responsible, alert and careful users (that watch what they click), you very well need nothing else besides maybe the built-in anti-virus that comes with Windows just so you can scan any files you download.
In a business network, there are other considerations where using an IDS/IPS or a tool such as pfBlockerNG with its geo-blocking capability is helpful to security. A great use of an IDS/IPS in a business network is to let it scan outbound traffic using rules that look for malware CNC server and botnet destinations, traffic destined to known untrusted countries, or any other traffic that should not normally be exiting your network. For example, if you have internal DNS servers that clients are configured to use, you could have a rule that would alert on any outbound DNS request that did not originate from your internal DNS server. Another handy thing for business networks would be using Snort's OpenAppID technology to identify non-work related traffic that violates a business policy.
I am not a fan of having a list of say a couple of million IP addresses that my firewall is actively blocking. I would instead turn that around and be much more specific with what I allow in and then let the default deny rule take care of everything else. Your firewall will sweat a lot less and you won't have memory and stability issues caused by having huge IP block lists. Do a quick search here on the forum for users posting about Unbound problems that are frequently the result of having huge DNS blacklists enabled. I know some folks use this feature for ad blocking, but I prefer to do ad blocking at the client level using tools like uBlock Origin in the browser. Between that and AdBlock for YouTube I don't see a single add on any web site I visit or any YouTube video I watch. Granted I'm an old fart and do my web browsing on a PC where the screen is big enough for me to see it ... . Maybe if all my browsing was on my iPad or iPhone, where ad blockers are not as prolific, I might go for something like Pi-Hole or DNSBL.
Just my two cents worth for the debate ...
Bill