In regards to Sam's advice. His advice is correct but people are interpreting it too strictly. Sam's advice is basically the baseline rules...as in you need to do this stuff AT LEAST to have a chance at being successful. This writing is not "do this stuff exactly and you will be successful 100% guaranteed".
The truth is....execution is the hard part and that's why most people fail. Building an amazing product that people love is hard. It really comes down to that...but if you want to be successful then that's what you need to do.