I will not talk more than without luck in gambling. We can play every game, even we have experience and also very well in all strategy but without luck that's all are useless.
Then your assumption is wrong. Even those who promotes luck over matters still does always advises everyone that it is just a bonus for everything you do just like gambling. Playing smart would still be more dominant than you were saying a pure luck.
Can anyone define luck? Anyway, I agree that there are certain games where the dominant factor is strategy and skill, but sometimes, the chance of the inferior team to win occurs. This is called an upset win, or bad beat in poker terms. I can say, chance to win or lose can never be omitted in a competition. Even with dice or roulette, it is that in this two gambling game, the chance to lose is pretty dominant because of it's ratio to winning.
"can anyone define luck?" Yes, of course there is luck is a word and a word wouldn't be made without any definition. The inferiority that you were saying is another situation as well because first those gambling sites were programmed to let the owner gain its profit and share some dividends to well as you said those lucky players that plays during that time.
I think he is not talking about the casino owner or program that is running within the site. It is a situation where a less favored player (underdog) win the match (upset win) while bad beat is the case in poker player where the one holding the inferior cards win.