I found the message of this episode to be in stark contrast to the vast majority of shonen series. Considering he is their teacher, he has a valid point, one we'd already seen proven.

Deku saved Uraraka, but in doing so, he would have died if not for her in turn saving him. What's the point of saving someone if you're just going to die in their place? It's a death either way. A hero can do more good by surviving and saving many more people.

Eraserhead was saying that a hero who is self-destructive is only a liability later. The usual shonen will have their hero/heroine pushing themselves beyond the limit, a broken tattered thing, before being saved by one of their allies at the last moment in dramatic fashion.

Eraserhead is saying that kind of behavior is unacceptable for their profession.