The article 'says' different than me but I'm gonna give you my medical opinion (I got my MD a few months back) in simple words.
HCG surpresses LH because it mimics it,raising testosterone. When we are on cycle that shutting down of LH doesn't matter because we are taking artificial testosterone that surpresses it anyway. So during cycle we use it only so our testes stay alive/big. When we come off testosterone it's time for natural LH to kick in. If you use HCG that mimics LH it's like saying to our body we don't need LH to come back up. So instead of helping recovery we are doing just the opposite,it's like prolonging our cycle. What Clomid and Nolva do is help our natural LH come back to natural levels plus help combat estrogen and that's why we use them for PCT.

English is not my mother language so if something I said wasn't clear feel free to ask about it.