That was good advice. You shouldn't start a new relationship to force yourself to forget another. If you haven't dealt with the emotional connection from the last relationship, and given yourself time to process your reaction, and maybe heal a bit, then you aren't doing yourself, or anyone else, any favours by engaging in a new relationship. That being said, we determine whether we allow ourselves to be influenced by our past relationships.
Your past relationships will always influence your future and present ones just don't let it affect it- you will learn lessons and use them accordingly. If you're dealing with heart break, going out with another girl will possibly make you forget about your last in the moment, however it could actually end up making you feel worse if you're not ready to move on and forcing yourself.