RAM timings, socket types, cooling selection, power supply selection, version/generation conflicts, Red vs Blue, will the GPU even fit in this computer case, counterfeit parts...

PCPartPicker.com exists, handles all this for you with giant "you missed something" red text if something won't work, and is one of the most commonly suggested beginner tools. If someone's complaining about being told to build their own, theyve been told about that tool

People get scared of a very simple task because people like you spread nonsense that makes it sound hard