It's okay, but I don't recommend just using that when doing research, and definitely don't use it to choose where to shop. Google shopping has far more shops listed. Just make sure you check individual sites as well. Many discounts aren't listed on the price comparison sites, like a 10% off sale at NewEgg.

There are still multiple parts from my build that aren't on PCPP. My motherboard's the MSI B450 Gaming Pro Carbon AC. It's one of the best reviewed boards around right now, and I can also vouch for it's awesomeness. If I stuck to PCPP, I'd never have heard of it. My case (AeroCool DS230 window edition) also isn't there, and that case (also awesome) came out over a year ago. Same with the monitor I'm getting once I'm less broke due to buying everything else.

PCPP's mostly useful for keeping a list and making it easy to share that list. It's fantastic for that, though. For everything else, don't underestimate the power of Google (searches like "best AM4 motherboards"), Google shopping, and searches on NewEgg. Even if you don't buy on NewEgg, their search feature has an insane amount of detail, letting you easily find parts that have every feature you need.