There are important reasons why students need to be able to spell. While spelling is one element of the writing process, it is a very visible one. Correct spelling contributes to meaningful communication when writing. Poor spelling affects the judgment of the reader and may reduce the credibility of the writer in their view. We expect those who write for academic or professional purposes to be able to spell correctly.
Students will generally avoid using words they cannot spell, even if they know the word. This can lead to limited vocabulary in written expression and an incorrect reflection of their knowledge and skills.
This example illustrates the point.
While spellcheck is a useful tool, it is not infallible and can lead to some bizarre writing.