Why treaty negotiators favored a 14-inch limit

Why did the major naval powers consider 14 inches an acceptable battleship-gun limit?

All three leading powers had practical 14-inch experience, and the smaller caliber made a 35,000-ton ship easier to balance.

Britain, the United States, and Japan all possessed practical experience with 14-inch guns or existing weapons in that caliber. That made 14 inches a negotiable common floor rather than an arbitrary British preference. Smaller guns also reduced the weight of turrets, ammunition, and the armor needed to resist comparable shells. Designers could use more of a 35,000-ton treaty allowance for speed, protection, endurance, or other capabilities. A treaty caliber limit could serve both diplomatic compromise and naval-architecture efficiency.