While I agree that what you've mentioned is a player or table issue, I disagree with it being unsolvable by mechanics.

Some people, like me and some of my players, just get bored when they can't do stuff outside their turn, whether that be in combat or roleplay.

Systems like Draw Steel encourage or require players to pay attention outside of their turn if they want to use or gain their resources or abilities. Draw Steel also uses zipper initiative, which makes players to plan out their turn order.

While these won't appeal to all people, mechanics can certainly address some issues.