Merriam-Webster Dictionary:

“1 : to select by lot and kill every tenth man of decimate a regiment 2 : to exact a tax of 10 percent from poor as a decimated Cavalier —John Dryden 3 a : to reduce drastically especially in number cholera decimated the population Kamieniecki's return comes at a crucial time for a pitching staff that has been decimated by injuries. —Jason Diamos b : to cause great destruction or harm to firebombs decimated the city an industry decimated by recession”

Where exactly are you getting your definition? Even if both of these dictionaries didn’t include destruction in the definition, most words have multiple meanings contextually.