I think it is just the nature of the market mechanism i.e. the rules of the game. Since markets are continuous there is going to be competition. Tick sizes mea

I think it is just the nature of the market mechanism i.e. the rules of the game. Since markets are continuous there is going to be competition. Tick sizes means that participants have to compete on speed rather than price. It seems to me that competition and continuous markets are maybe the best way to keep prices aligned across markets. And, just maybe, the best way to keep costs low for retail traders.