English is not my first language, but when I started using Firefox with the built-in spell correction, I firmly believe my ability to spell words went drastically up. My grammar is stiff iffy, like I'm pretty sure I do comma splices everywhere, but at least most people can understand what I say now compared to when I was 13 and on the internet.

If there was a "gramma nazi" teenie tiny LLM with a total focus on English grammar only, and you baked that into every browser, I feel like my grammar would improve slightly. Word does it to an extent, but I don't use Word nearly enough for it to be meaningful. Firefox text spell checking was on 98% of the things I used online.