I don't think eating 6 meals a day is bad advice, it's just not necessary for everyone. Many bodybuilders follow this "bro science", so there is some truth to it.
I think it's more of a eating habit to make sure people:
1. Don't overeat between meals or snack.
2. Eat regularly and don't skip meals.
There was a study I posted up last year that tested people who ate more frequently than others. Some people responded better to smaller infrequent meals and some responded better to almost a intermittent fasting approach.