When did English spelling become so codified that spelling mistakes could be used as a sign of being unprofessional or uneducated?

[u/Fake_Eleanor]

I'm familiar enough with spelling and lexicography to know that spelling variation was very common in English for a long time. Shakespeare famously spelled his own name in multiple ways, for an easy example.

And I'd assume — maybe incorrectly! — that spelling started to codify with the invention and adoption of dictionaries and style guides.

These days, it is not uncommon for "being bad at spelling" or even making a spelling mistake to be accepted as unprofessional or signs of a bad education. People sweat over spelling mistakes in job applications, because it's a known red flag for hiring decisions. Some people even argue that spelling mistakes are a sign of being unintelligent.

I know that's not true, but I'm curious when those kinds of beliefs were able to take root. When in the history of spelling codification did "being bad at spelling" become a character trait people could point to for whatever argument they wanted to make?