All Open is the most skilled a game of Triple Triad can be simply because you know what your opponent has and can plan around it, bait them into certain spots and overall read the flow of the game.
When you are unable to see your opponent's cards, you simply do not know what they have or where they are strong. For example, if you knew your opponent's deck was fairly weak on top, you could purposefully play cards near the bottom to put them into bad situations. Without this knowledge, it's simply a game of placing your dominant 8 faces outwards, covering your weaknesses as best you can and waiting for the moment where your 5 star card can take you to victory. But until that moment, you either can turtle your cards or place a card somewhere weird to take back later.
Since you have no idea what your opponent has left, you can't actually form a strategy beyond building your own. At the very best, you can try to set up to place your 5 star in a position to take a card or two and win. This results in every game effectively being the same.
All Open shouldn't be a ruleset but rather how the game itself works. Without being able to see your opponent's deck, you're often in positions where you just place cards where they are strongest, instead of actually using skill to manipulate your opponent's weaknesses.