...and yet the first thing I switch off in every tool is the spellchecker, because they get utterly confused with the mix of English, German and my local dialect that I'm using when communicating with different people. I'd say doing a spellchecker "right" is apparently still a major feat of software engineering ;)
I often write in a mixture of Scots and English, and spellcheckers are nae guid for that use case. The problem is solved, however, on iOS and Android thanks to SwiftKey[1]. [1] https://dsl.ac.uk/our-publications/scots-predictive-keyboard...
Honestly I can't use the default keyboard in iOS anymore because it lacks multilingual support. How it still isn't a thing in 2020 boggles me.