Blackjack, roulette etc. are purely luck based and the house will always win in the long run. That's not allowed.
Disagreement with Blackjack. It does take skill.
I can concede that roulette is more luck-based. Unless, you visit some of the casinos with old school wooden ones that are somewhat worn out.
You are right, blackjack was a bad example, you can beat the house with special techniques. It's difficult to find perfect definitions and that shows that there are a lot of grey areas. We are changing that part. Thanks for telling us!