Yes, absolutely, our system does a bad job of teaching grammar! If people learn it, they mostly learn it, like you, via learning a second language. My high school English teachers were very old school, so we did a lot of diagramming and stuff like that, but I know that my experience was not typical.

One shift I like that I think about a lot is using "impact" as a verb, which was technically not correct when I was in high school - it was only a noun.

Oooh, yeah, that's a major shift!