Maybe that question is to clear out his doubts to use dome strategies he read up used by other people and same as you said there's nothing wrong to use it or any other else as long as there's no exploiting or other abusive things they do on the casino. To many people use that and experimenting other strategy to use and they are fine so they should try it since somehow those strategy mentioned is really fun to use.
You can use whatever strategy you like because it's dependent on your mindset but martingale is not too much fun if you have limited bankroll because of it's aggressive betting behavior in order to win but still we all have different opinions in gambling and for some it may work while for others it's the same.