The reason why I reject conventions and want to play by logic only is my philosophy, how I see this amazing game, i.e. as a logic game. And also self reward.

I suppose we all (or most of us do) play cooperative games for how rewarding it is to beat the game. Once you have beaten the easy mode, you want to switch to medium, then hard mode. How fun and rewarding would it be to win in easy mode all the time? Not much.

In Hanabi, I find pleasure in thinking, analysing a situation and figuring out the logic in the clues that my teammates give.

For me, using conventions in hanabi is by-passing the amazing richness of the game, by-passing the great challenge it displays, playing in easy mode. Conventions like leftism, anyone could use them, even beginners. Conventions get you a good score, ok, you may feel glad, but what was your actual personal contribution to that good score, except for applying in a soulless way the get-rich-quick scheme that was "written in the book"?

In opposition, playing a game where you try and find the twisted meanings for your teammates' clues by yourself,  with no other artifice than your experience and logical mind, getting a good score and being able to think to yourself "damn, we've been good and we only owe it to our analysis of every situation!", that is freaking awesome.

The logical way does takes much more thinking effort and time to master, but it makes the game immensely more challenging and interesting (for who likes challenges).

Also, it turns out that logical leftism can make you work around some situations conventional leftism can't handle.

Hanabi is not about "solving" the game with computers or artificial conventions, it is about challenge.

Situation is everything.