Most of the spelling errors in their post were 'wrong word' errors, aka the [Cupertino effect][0]. A spell checker would not have found those. It's possible the

Most of the spelling errors in their post were 'wrong word' errors, aka the [Cupertino effect][0]. A spell checker would not have found those. It's possible they were also relying on auto-completion, which increases this type of error. [0]: https://en.wikipedia.org/wiki/Cupertino_effect https://en.wikipedia.org/wiki/Cupertino_effect