If we look back at th7, you get an extra army camp (50 troop capacity) as well as an extra barrack for those 50 spaces. Resulting in one barrack to 50 troops. Then one barrack to 55 troops at th9.
Now th10 have a 240 camp capacity, I think its justified to an additional barrack for th10 to bring the ratio back down to one barrack to 48 troops.
Thoughts?

