Sometimes injuries just happen. I know, it's crazy!

Also, penalty cards.

It's not a conspiracy or evil game design. Every single one of you watches irl Football and knows that accidents can occur at any moment - It's a taxing sport.

And as @Khris explains - with the injuries update we deployed at the end of 2015, clubs en masse are easily stockpiling Treatments due to how rare it is to get an injury these days.

Below are the 3 things that the injuries update changed back then:
- Scout players won't be injured for some period after they were bought.
- Players won't get injured several times in a row. (NOTE: This doesn't mean that it's impossible for several DIFFERENT players to get injured one after the other.)
- Only one injury may occur during a live match PER team.

EDIT: Oh and ofc. players can no longer get injured while training, so there's that too.