Boku no Hero Academia

[Ryllharu]

What exactly does "subverted trope" mean to you?

It isn't take trope and do the literal opposite. It's merely bait trope setup, but do something different.

The expectation is that a sacrifice is heroic. The realization in this series is that it is viewed as worse than doing nothing.

All Might has that view point because he is so strong that it doesn't ever really happen. Eraserhead and the other teachers obviously believe otherwise. What Izuku did in the exam was reckless. What if the school nurse wasn't around? Izuku would be in traction for months, then rehab for years. Her existence is to allow students to cut loose. The teachers have a different viewpoint once the students are enrolled.

Don't forget that All Might is teaching there for the first time. The other teachers are veterans.