I am assuming that many (most?) of the startup founders, when they are being interviewed by the potential investors, are 'complete strangers'. By focusing objectively on ideas than subjectively or intuitively on people doing them, they believe that they mitigate the so-called risk. I am not convinced that by judging people rather than by judging ideas (in supposedly short amount of time) the chances of succeeding go up, because if we are often wrong judging ideas, what makes us good at judging people who are ever changing too?
Of course, there is an undeniable 'credit history' part wherein if a 'successful' founder comes back with another idea, many investors are ready to 'shower money' on her/him -- I don't find anything majorly wrong with that attitude, but that alone does not guarantee success, I believe.